Chapter 6. Project schedule management: Getting it done on time

Figure 6-1.  

Project schedule management is what most people think of when they think of project managers. It’s where the deadlines are set and met. It starts with figuring out what work you need to do, how you will do it, what resources you’ll use, and how long it will take. From there, it’s all about developing and controlling that schedule.

Reality sets in for the happy couple

Rob and Rebecca have decided to tie the knot, but they don’t have much time to plan their wedding. They want the big day to be unforgettable. They want to invite a lot of people and show them all a great time.

But just thinking about all of the details involved is overwhelming. Somewhere around picking the paper for the invitations, the couple realize they need help…

Figure 6-2.  

Meet the wedding planner

Figure 6-3.  

Rob: We want everything to be perfect.

Rebecca: There is so much to do! Invitations, food, guests, music…

Rob: Oh no, we haven’t even booked the place.

Rebecca: And it’s all got to be done right. We can’t print the invitations until we have the menu planned. We can’t do the seating arrangements until we have the RSVPs. We aren’t sure what kind of band to get for the reception, or should it be a DJ? We’re just overwhelmed.

Rob: My sister said you really saved her wedding. I know she gave you over a year to plan.

Rebecca: But I’ve always dreamed of a June wedding, and I’m not willing to give that up. I know it’s late, but can you help us?

Brain Power

What should Kathleen do first to make sure they have time to get everything done?

Schedule management helps with aggressive timelines

Since there are so many different people involved in making the wedding go smoothly, it takes a lot of planning to make sure that all of the work happens in the right order, gets done by the right people, and doesn’t take too long. That’s what the Project Schedule Management knowledge area is all about.

Initially, Kathleen was worried that she didn’t have enough time to make sure everything was done properly. But she knew that she had some powerful time management tools on her side when she took the job, and they’ll help her make sure that everything will work out fine.

Figure 6-4.  

Project Schedule Management Magnets

You need to know the order of the Project Schedule Management processes for the exam. Luckily, they are pretty intuitive. Can you figure out the order?

Figure 6-5.  

Figure 6-6.  

Project Schedule Management Magnets Solution

Here are the correct order and the main output for each of the Project Schedule Management processes.

Figure 6-7.  

Figure 6-8.  

Figure 6-9.  

Figure 6-10.  

Brain Power

Project Schedule Management is all about breaking the work down into activities, so you can put them in order and come up with estimates for each of them.

What do you need to know before you can figure out what activities are needed for a project?

Plan your scheduling processes

The Plan Schedule Management process is just like all of the other planning processes you’ve seen so far. In fact, you’ve already seen all of the inputs and tools that are used to create it in previous processes. Just like with the Plan Scope Management process from Chapter 5, your goal is to build a Schedule Management plan from the other project management plans, your company’s culture and existing documents, and the project charter.

Figure 6-11.  

Figure 6-12.  

Now you know how you’ll track your schedule

The only output of the Plan Schedule Management process is the Schedule Management plan. It describes the way you’ll estimate your work, track your progress, and report on it.

Figure 6-13.  

Figure 6-14.  

Use the Define Activities process to break down the work

Define Activities uses everything we already know about the project to divide the work into activities that can be estimated. The inputs for this process all come from the processes in the Integration Management knowledge areas. The first step in Project Schedule Management is figuring out how the project work breaks down into activities—and that’s what the Define Activities process is for.

Figure 6-15.  

Figure 6-16.  

Tools and techniques for Define Activities

Kathleen wrote down everything she knew about the project. She used the activity list from her last wedding as a guide and then thought about the things that Rob and Rebecca wanted that were different from her past projects. She broke those things down into activities and pulled everything together into an activity list.

Figure 6-17.  

Decomposition This means taking the work packages you defined in the Scope Management processes and breaking them down even further into activities that can be estimated.	Figure 6-18.
Expert judgment Ask somebody who has done this before to give an opinion on what activities will be needed to get the job done.	Figure 6-19.
Rolling wave planning When you plan this way, you decompose only the activities that you need to plan for because they’re coming up soon. You leave everything else planned at the milestone level until it gets closer to the time when you’ll do it.	Figure 6-20.
Meetings You’ll need to talk to the team to figure out what they think they need to do to achieve your project’s goals. Getting the team together to discuss the plan will be a useful tool when you’re defining the activities in your schedule.	Figure 6-21.

Rolling wave planning lets you plan as you go

Sometimes you start a project without knowing a lot about the work that you’ll be doing later. Rolling wave planning lets you plan and schedule only the stuff that you know enough about to plan well.

Figure 6-22.  

If Kathleen were using rolling wave planning, she might write a schedule for only the tasks it takes to do the invitations, and leave the planning for the menu and the seating up in the air until she knows who will RSVP.

Rob and Rebecca probably wouldn’t be happy hearing that Kathleen was only going to plan for the invitations to be sent, though. They want to know that their wedding is going to happen on time. That’s why rolling wave planning should be used only in cases where it’s not possible to plan any other way.

Think back to the definition of a project in Chapter 2. Remember how projects are progressively elaborated? Rolling wave planning takes advantage of the fact that you know more about the project as you go to make plans more accurate.

there are no Dumb Questions

Q: How would you use experts to help you define tasks?

A: A wedding is something that a lot of people have experience with, but some projects are not as easy to get a handle on. If you were asked to manage a project in a new domain, you might want to ask an expert in that field to help you understand what activities were going to be involved.

Even in Kathleen’s case, access to a catering expert might help her think of some activities that she wouldn’t have planned for on her own.

It could be that you create an activity list and then have the expert review it and suggest changes. Or, you could involve the expert from the very beginning and ask to have a Define Activities conversation with him before even making your first draft of the activity list.

Q: I still don’t get rolling wave planning.

A: One way to develop a project is to divide it up into phases of work, and gather requirements for each phase as the previous one is completed. Sometimes projects are done iteratively, where you divide the work up into phases and then plan out each phase before you execute on it. Rolling wave planning is all about committing to planning out one portion of the work that you’ll do, executing it, and then moving on to the next portion.

Software projects using agile methodologies use a form of rolling wave planning to make sure that everything they sign on to do gets done. They might do user stories for a release of the software up front, build it, and deliver it, and then gather more requirements based on the users’ ideas after working with the released version.

Activity Magnets

Here is part of a WBS. Arrange the activities underneath the WBS to show how the work items decompose into activities.

Figure 6-23.  

Figure 6-24.  

Activity Magnets Solution

Here is part of a WBS. Arrange the activities underneath the WBS to show how the work items decompose into activities.

Figure 6-25.  

Figure 6-26.  

Define activities outputs

The main output of this process is the activity list. It’s the basis for all of the estimation and scheduling tasks you will do next. But there are a few other outputs that go along with it, and help to make the estimates more detailed and accurate.

Figure 6-27.  

Activity list

This is a list of everything that needs to be done to complete your project. This list is lower-level than the WBS. It’s all the activities that must be accomplished to deliver the work packages.

Activity attributes

Here’s where the description of each activity is kept. All of the information you need to figure out the order of the work should be here, too. So any predecessor activities, successor activities, or constraints should be listed in the attributes, along with descriptions and any other information about resources or time that you need for planning.

Milestone list

All of the important checkpoints of your project are tracked as milestones. Some of them could be listed in your contract as requirements of successful completion; some could just be significant points in the project that you want to keep track of. The milestone list needs to let everybody know which are required and which are not. Note Some milestones for the wedding: Invitations sent Menu finalized Church booked Bridesmaids’ dresses fitted

Change requests

As the team is working through the work they’ll do, they sometimes find new information about the scope or requirements of the project. When that happens, they’ll need to create a change request to update the scope of the project.

Project Management plan updates

When the team identifies new activities there will likely be changes to both the schedule baseline and the cost baseline. You’ll need to put those changes through change control and then update the Project Management plan to include the new activities.

Figure 6-28.  

Rob: The quartet cancelled. They had another wedding that day.

Rebecca: Aunt Laura is supposed to do the reading at the service, but after what happened at Uncle Stu’s funeral, I think I want someone else to do it.

Rob: Should we really have a pan flute player? I’m beginning to think it might be overkill.

Rebecca: Maybe we should hold off printing the invitations until this stuff is worked out.

Kathleen: OK, let’s think about exactly how we want to do this. We need to be sure about how we want the service to go before we do any more printing.

The Sequence Activities process puts everything in order

Now that we know what we have to do to make the wedding a success, we need to focus on the order of the work. Kathleen sat down with all of the activities she had defined for the wedding and decided to figure out exactly how they needed to happen. That’s where she used the Sequence Activities process.

Figure 6-29.  

The activity attributes and the activity list she had created had most of the predecessors and successors written in them. Her milestone list had major pieces of work written down, and there were a couple of changes to the scope she had discovered along the way that were approved and ready to go.

Figure 6-30.  

Diagram the relationship between activities

One way to visualize the way activities relate is to create a network diagram. Kathleen created this one to show how the activities involved in producing the invitations depend on one another.

Figure 6-31.  

For example, the calligrapher is the person who’s hired to write the addresses on the invitations, so Rob and Rebecca need to pick one before the invitations can be addressed. But the invitations also need to be printed before they can be addressed, because otherwise the calligrapher won’t have anything to write on! See how predecessors can get all complicated? Luckily, a diagram makes sense of them!

Showing the activities in rectangles and their relationships as arrows is called a precedence diagramming method (PDM).

Figure 6-32.  

Network diagrams put your tasks in perspective

Just looking at the way all of these tasks relate to one another can help you figure out what’s important at any time in the project. Once Rob and Rebecca looked at the network diagram below, they realized they needed to get online and start looking for a venue for their wedding right away, even before they’d figured out their budget and guest list.

Figure 6-33.  

Brain Power

Think of a few problems that having a diagram like this might solve.

Sharpen your pencil

You’ll need to know how to turn a table of nodes into a network diagram, so here’s your chance to get some practice! Here’s a list of nodes for a PDM network diagram. Try drawing the diagram based on it:

Name	Predecessor
Start	—
A	Start
B	A
C	B
D	Start
E	D
F	B
G	C
H	D
I	E, H
Finish	F, G, I

Name	Predecessor
Start	—
1	Start
2	1
3	2
4	Start
5	3
6	Start
7	6
Finish	7, 4, 5

Answers in “ Sharpen your pencil Solution”.

Dependencies help you sequence your activities

The most common kind of dependency is the Finish to Start. It means that one task needs to be completed before another one can start. There are a few other kinds of dependencies, though. They can all be used in network diagrams to show the order of activities. The three main kinds of dependency are Finish to Start (FS), Start to Start (SS), and Finish to Finish (FF). This tool is called dependency determination and integration in the Sequence Activities process.

Figure 6-34.  

External dependencies

Sometimes your project will depend on things outside the work you are doing. For the wedding, we are depending on the wedding party before us to be out of the reception hall in time for us to decorate. The decoration of the reception hall then depends on that as an external dependency.

Discretionary dependencies

Rob and Rebecca really want the bridesmaids to arrive at the reception before the couple. There’s no necessity there—it’s just a matter of preference. For the exam, know that you should set discretionary dependencies based on your knowledge of the best practices for getting the job done.

Mandatory dependencies

You can’t address an invitation that hasn’t been printed yet. So, printing invitations is a mandatory dependency for addressing them. Mandatory dependencies are the kind that have to exist just because of the nature of the work.

Internal dependencies

The rehearsal dinner can’t begin until the happy couple leaves the church. Some dependencies are completely within the team’s control.

Leads and lags add time between activities

Sometimes you need to give some extra time between activities. Lag time is when you purposefully put a delay between the predecessor task and the successor. For example, when the bride and her father dance, the guests wait awhile before they join them.

Lead time is when you give a successor task some time to get started before the predecessor finishes. So you might want the caterer preparing dessert an hour before everybody is eating dinner.

Figure 6-35.  

there are no Dumb Questions

Q: Where do you get the dependency information to figure out your network diagram?

A: Your activity attributes should list the predecessors and successors for each activity. As you build the network diagram, you might discover new dependencies as well. Your project team will determine the dependencies necessary for each of the activities.

Q: What about Start to Finish dependencies?

A: It’s possible for activities to require that a task has been started before it can finish. An example might be that singing couldn’t start until after the music had started. But tasks like that are pretty rare and almost never show up in network diagrams.

Q: My scheduling software makes network diagrams for me. Why do I need to know this?

A: Most scheduling software does create one of these diagrams automatically. But spending the time to think through your dependencies and examine them visually can really help you find places where you might need to give some tasks more priority if you want to get your project done on time. So you should know how to make them too.

Scheduling software can help you see the sequence of activities

Many people use applications like Microsoft Project to visualize their activity list and organize their dependencies. Taking the time to really understand the best sequence of activities can have a real impact on your project’s deadlines, so using software like that as part of your company’s project management information system is a good way to get a handle on just the right sequence for your project to run efficiently.

Figure 6-36.  

Figure 6-37.  

You should still think of things in sequence.

For the test, it’s important to know the order of these processes. And even though you might do it all at once, you probably spend some time thinking about each of these things.

Brain Power

What’s the advantage of thinking about Define Activities and Sequence Activities separately?

Create the network diagram

As you sequence the activities, you will find new activities that need to be added and new attributes for activities that you didn’t know about. So, while the main product of this process is the network diagram, you also produce updates to some of the Define Activities documents and outputs of other processes, too.

Figure 6-38.  

Figure 6-39.  

Figuring out how long the project will take

Once you’re done with Sequence Activities, you’ve got everything you need to figure out how long each activity will take. That’s done in a process called Estimate Activity Durations. This is where you look at each activity in the activity list, consider the scope and the resources, and estimate how long it will take to perform.

Figure 6-40.  

Figure 6-41.  

Exercise

You’ll need to understand the various inputs and outputs for each process for the exam. Here’s a list of some of the project documents and other inputs for Estimate Activity Durations. Write down what you think each of them will be used for when you actually sit down and estimate how long each activity will take.

1. Activity list and activity attributes

2. Activity resource requirements

3. Project scope statement

4. Enterprise environmental factors

5. Organizational process assets

Exercise

You’ll need to understand the various inputs and outputs for each process for the exam. Here’s a list of some of the inputs for Estimate Activity Durations. Write down what you think each of them will be used for when you actually sit down and estimate how long each activity will take.

1. Activity list and activity attributes

   Contains information about the activities that are being estimated

   Note

   You need these because the goal of this process is to estimate the duration of each activity.

2. Activity resource requirements

   Shows which resources are assigned to each activity

   Note

   The more resources you add to an activity, the less time it takes.

   Note

   But sometimes adding people won’t get the job done any faster! Remember, nine women can’t have a baby in one month.

   Note

   You’re probably not the first person in your company to do this sort of project. Information from people around you will be very valuable when you’re creating estimates.

3. Project scope statement

   Lists constraints and assumptions for each activity

   Note

   This input is always about looking elsewhere in your organization for information.

4. Enterprise environmental factors

   Other people or databases in my company can help with estimation

   Note

   Any time you see this, think about historical information and project records!

   Note

   The more you know about how past projects went, the more accurate your estimates will be.

5. Organizational process assets

   Contains historical information and records from past projects

Estimation tools and techniques

Estimating the duration of an activity means starting with the information you have about that activity and the resources that are assigned to it, and then working with the project team to come up with an estimate. Most of the time you’ll start with a rough estimate and then refine it (maybe a few times!) to make it more accurate. You’ll use these tools and techniques to create the most accurate estimates.

Figure 6-42.  

Expert judgment will come from your project team members who are familiar with the work that has to be done. If you don’t get their opinion, then there’s a huge risk that your estimates will be wrong!

Parametric estimating means plugging data about your project into a formula, spreadsheet, database, or computer program that comes up with an estimate. The software or formula that you use for parametric estimating is built on a database of actual durations from past projects.

Bottom-up estimating means building your estimates up based on individual estimates from the people who will do the work.

Data analysis means using reserve analysis to add extra time to the schedule (called a contingency reserve or a buffer) to account for extra risk. It can also mean using alternatives analysis to think through all of the possible options to find the most efficient path for delivery.

Analogous estimating is when you look at activities from previous projects that were similar to this one and see how long it took to do similar work for them. But this only works if the activities and the project team are similar!

Three-point estimates are when you come up with three numbers: a most likely estimate that probably will happen, an optimistic one that represents the best-case scenario, and a pessimistic one that represents the worst-case scenario. The final estimate is the average.

Decision-making techniques help the team decide on the best estimates for the activities they’ve defined.

Meetings help teams to work together when they estimate the work.

Exercise

Each of these scenarios describes a different tool or technique from Estimate Activity Durations. Write down which tool or technique is being described.

1. Kathleen comes up with three estimates (one where everything goes wrong, one where some things go wrong, and one where nothing goes wrong) for printing invitations, and averages them together to come up with a final number. ...........................

2. There will be two different catering companies at the wedding. Kathleen asks the head chef at each of them to give her an estimate of how long it will take to do the job. ...........................

3. There’s a spreadsheet Kathleen always uses to figure out how long it takes guests to RSVP. She enters the number of guests and their zip codes, and it calculates an estimate for her. ...........................

4. Kathleen’s done four weddings that are very similar to Rob and Rebecca’s, and in all four of them it took exactly the same amount of time for the caterers to set up the reception hall. ...........................

Answers in “ Exercise Solution”.

Three-Point Estimates Up Close

Figure 6-43.  

PERT (Program Evaluation Review Technique) is the most common form of three-point estimation. It’s a technique that was developed in the 1960s by consulting firms working with the US government as a way of getting more accurate project duration predictions up front. To do a PERT estimate, you start with three estimates—pessimistic, most likely, and optimistic estimates. (The formula used for PERT estimates is called beta distribution.) Since the pessimistic and optimistic estimates are less likely to happen than the normal estimate, the normal estimate is weighted (multiplied by 4) and added to the optimistic and pessimistic estimates, and then the whole thing is divided by 6 to give an expected duration. The formula looks like this:

Figure 6-44.  

Kathleen used a PERT estimate for all of the wedding planning activities to make sure that she could get it all done in time for Rob and Rebecca’s big day. They only have six months until the wedding, so all of the planning needs to be done within the month to leave enough time to actually finish everything. She wrote down the assumptions she made for each estimate, coming up with all of the reasons she could think of that she took into account when coming up with her estimates.

Note

An assumption is a decision that you make to account for things you don’t know when you make an estimate.

Figure 6-45.  

Exercise

Here are some examples of three-point estimates. Use the formula to figure out the expected time for each of these.

1. A software team gathered estimates for all of the work they’d have to do to build the next major release of their flagship product. Last time it took them around 45 days, but they’re hoping that the lessons learned from the past release could bring the time down to 30 days. However, the infrastructure team needs to upgrade their servers, and they are concerned that procurement delays could potentially extend the project out to 90 days.

   Expected duration = __________	Optimistic duration = __________	Most likely duration = __________
   Pessimistic duration = __________

2. A construction team gathered estimates for all of the work they’d have to do to build a garage. In general, they can build a garage in 20 days, but rain or cooler temperatures could stretch the project out to 30 days. If, however, the forecast is correct, warm, sunny weather might bring the duration down to just 12 days.

   Expected duration = __________	Optimistic duration = __________	Most likely duration = __________
   Pessimistic duration = __________

3. A project manager used data from past projects to come up with an estimate for an upcoming software system replacement project. She felt confident about a 25-day duration, but also noted that adding an extra resource could bring the schedule down to 10 days. The test team felt that the complexity of some completely new features would add additional test cases, adding a few weeks for a 40-day estimate.

   Expected duration = __________	Optimistic duration = __________	Most likely duration = __________
   Pessimistic duration = __________

4. A project manager in charge of a big civil engineering project came up with an estimate for a highway repaving project. The worst-case scenario was 82 days, but the team felt more certain based on past experience that they could get it done in 49 days. If all went well with their equipment and materials, it might be done in 33 days instead.

   Expected duration = __________	Optimistic duration = __________	Most likely duration = __________
   Pessimistic duration = __________

Answers in “ Exercise Solution”

Create the duration estimate

You’ve got a list of activities, you know what resources are needed to actually do each activity, and you’ve got your estimation tools and techniques…now you have enough to create the estimates! That’s the whole point of the Estimate Activity Durations process, and it’s also the main output.

Figure 6-46.  

The activity duration estimates are estimates of how long each activity in the activity list will take. The estimate can be in hours, days, weeks…any work period is fine, and you’ll use different work periods for different jobs. A small job (like booking a DJ) may just take a few hours; a bigger job (like catering—including deciding on a menu, ordering ingredients, cooking food, and serving guests on the big day) could take days. You’ll also a produce a basis of estimates document that describes your approach, the assumptions you made, and factors you considered.

Note

You don’t always know exactly how long an activity will take, so you might end up using a range (like 3 weeks +/- 2 days).

You’ll also learn more about the specific activities while you’re estimating them. That’s something that always happens—you have to really think through all of the aspects of a task in order to estimate it. So the other output of Estimate Activity Durations is updates to the project documents.

You may have guessed from the name that the activity duration estimates are always duration estimates, not effort estimates, so they show you calendar time and not just person-hours.

Figure 6-47.  

The activity duration estimate consists of estimates for each activity. It’s the main output of the Estimate Activity Durations process.

there are no Dumb Questions

Q: When you use parametric estimation, how does the program or formula know how much to estimate?

A: When people design a system for parametric estimation, they collect a lot of data from past projects and condense it into a table or a database. And then they come up with a heuristic (like a rule of thumb) that lets you boil your estimation down into just a few parameters that you need to enter. Most successful parametric estimation systems need a lot of time to develop.

Q: Since reserve analysis lets me use buffers, why can’t I just put everything I don’t know about into the reserve?

A: The idea behind reserve analysis is that there are always unknowns on any project, but you can account for these unknowns by taking your best guess at what’s going to go wrong and inserting a buffer. But you can’t just make an enormous reserve, because then there’s no reason to ever do any estimation! The entire project becomes one big unknown, and that’s not particularly useful to anyone.

Q: Wait a minute! I don’t quite get the difference between a duration estimate and an effort estimate. Can you explain?

A: Duration is the amount of time that an activity takes, while effort is the total number of person-hours expended. If it takes two people six hours to carve the ice sculpture for the centerpiece of a wedding, the duration is six hours. But since two people worked on it for the whole time, it took 12 person-hours of effort to create!

Back to the wedding

Kathleen’s really got a handle on how long things are going to take, but that’s not enough to get the job done. She’s still got some work to do before she’s got the whole project under control.

Figure 6-48.  

Figure 6-49.  

Brain Power

It’s not easy to plan for a lot of resources when they have tight time restrictions and overlapping constraints. How would you figure out a schedule that makes everything fit together?

Bringing it all together

The Develop Schedule process is the core of Project Schedule Management. It’s the process where you put it all together—where you take everything you’ve done so far and combine it into one final schedule for the whole project. A lot of project managers consider this the most important part of their job. The schedule is your most important tool for managing a project.

Figure 6-50.  

Figure 6-51.  

Develop Schedule brings everything you’ve done so far together into one final schedule. All of the outputs from the other Project Schedule Management processes are inputs to Develop Schedule.

Don’t worry, even though you’re done with the Estimate Activity Durations process, you’re not done with the resources.

You’re never going to have the complete resource picture until you’re done building the schedule. And the same goes for your activity list and duration estimates, too! It’s only when you lay out the schedule that you’ll figure out that some of your activities and durations didn’t quite work. We’ll go in depth about resources when we talk about Project Resource Management in Chapter 9.

Figure 6-52.  

Note

That’s why the processes have the word “Estimating” in their names! Because you’re taking an educated guess, but you won’t know for sure until you’ve actually developed the schedule.

Figure 6-53.  

Each of the processes allows updates to an output from a previous one, so when you discover changes, you can include them in the schedule.

Question Clinic: The which-comes-next question

Figure 6-54.  

Head Libs

Fill in the blanks to come up with your own which-comes-next question! Start by thinking of a process to be the correct answer, and then figure out which process came right before it—that’s the one you’ll describe in the question!

Figure 6-55.  

One thing leads to another

Figure 6-56.  

Rebecca: Well, let’s see. What menu did we give to the caterers?

Rob: We didn’t give it to them yet, because we won’t have the final menu until everyone RSVPs and lets us know which entrée they want.

Rebecca: But they can’t RSVP because we haven’t sent out the invitations! What’s holding that up?

Rob: We’re still waiting to get them back from the printer. We can’t send them out if we don’t have them yet!

Rebecca: Oh no! I still have to tell the printer what to print on the invitations, and what paper to use.

Rob: But you were waiting on that until we finished the guest list.

Rebecca: What a mess!

Note

…but it turns out to be a lot bigger than either Rob or Rebecca realized at first! How’d a question about one guest’s meal lead to such a huge mess?

Brain Power

Can you think of a situation where a delay in an activity early on in a project can lead to a problem in a later activity, which leads to another problem in another activity, leading to a cascade of problems that makes the project late?

Use the critical path method to avoid big problems

The critical path method is an important tool for keeping your projects on track. Every network diagram has something called the critical path. It’s the string of activities that, if you add up all of the durations, is longer than any other path through the network. It usually starts with the first activity in the network and usually ends with the last one.

The reason that the critical path is, well, critical, is that every single activity on the path must finish on time in order for the project to come in on time. A delay in any one of the critical path activities will cause the entire project to be delayed.

The critical path is the string of activities that will delay the whole project if any one of them is delayed.

Figure 6-57.  

How does knowing your critical path help?

Knowing where your critical path is can give you a lot of freedom. If you know an activity is not on the critical path, then you know a delay in that activity may not necessarily delay the project.

This can really help you handle emergency situations. Even better, it means that if you need to bring your project in earlier, you know that adding resources to the critical path will be much more effective than adding them elsewhere.

How to find the critical path

It’s easy to find the critical path in any project! With a little practice, you’ll get the hang of it. Of course, on a large project with dozens or hundreds of tasks, you’ll probably use software like Microsoft Project to find the critical path for you. But when it does, it’s following the same exact steps that you’ll follow here.

1. Start with an activity network diagram.

   

   Figure 6-58.  

2. Find all of the paths in the diagram. A path is any string of activities that goes from the start of the project to the end.

3. Find the duration of each path by adding up the durations of each of the activities on the path.

   

   Figure 6-59.  

The critical path is the one with the longest duration!

Exercise

You may get questions on the exam asking you to identify the critical path in a network diagram. Here’s some practice for doing that! Find the critical path and duration for these PDMs.

Figure 6-60.  

Answers in “ Exercise Solution”.

Finding the float for any activity

Note

The goal is to find the float for each activity. We’re not really concerned with finding a total float for each path—we’re looking at the activities independently.

Once you’ve figured out the critical path, there’s all sorts of useful stuff you can do with it. One of the most useful things you can do is calculate the float. The float for any activity is the amount of time that it can slip before it causes your project to be delayed. You might also see the word slack—it’s the same thing.

Luckily, it’s not hard to figure out the float for any activity in a network diagram. First you write down the list of all of the paths in the diagram, and you identify the critical path. The float for every activity in the critical path is zero.

1. There are three paths in this network:

   Start → A → B → C → Finish = 11

   Note

   The path with the longest duration is the critical path!

   Start → D → E → Finish = 7

   Start → D → F → G → Finish = 8

   

   Figure 6-61.  

2. The float for each of the activities on the critical path is zero.

   

   Figure 6-62.  

3. Find the next longest path. Subtract its duration from the duration of the critical path, and that’s the float for each activity on it.

   Note

   That’s how you figure out how long any of its activities can slip before it delays the project.

   

   Figure 6-63.  

4. Do the same for the next longest path, and so on through the rest of the network diagram. Pretty soon, you’ll fill in the float for every activity!

   Note

   This is why you figure out the length of each path before you start.

   

   Figure 6-64.  

You can use this method to find the float for every activity in a network diagram. Another word for float is slack.

Float tells you how much extra time you have

Once you know the float, you know how much play you have in your schedule. If an activity has a float of 2 days, it can slip by that much without affecting the end date.

Figure 6-65.  

To find the float for an activity, figure out how much it can slip before it makes the project late. The float for any activity on the critical path is ZERO!

Exercise

You’ll need to be able to calculate the float of an activity in a network diagram for the exam. Take another look at this PDM from the last exercise. Can you calculate the float for each activity?

Figure 6-66.  

Answers in “ Exercise Solution”.

there are no Dumb Questions

Q: Where do the duration numbers come from on each activity?

A: A lot of people ask that question. It’s easy to forget that everything you do in Sequence Activities builds on the stuff you did in the other Project Schedule Management processes. Remember the estimates that you came up with during Estimate Activity Durations? You used techniques like three-point estimates, analogous estimating, and parametric estimating to come up with an estimate for each activity. Those are the estimates that you use on your network diagrams!

Q: What if there’s a path that’s not critical, but where even a small slip in one activity would delay the project?

A: This is exactly why it’s important to know the float for each of your activities. When you’re managing your project, it’s not enough to just pay attention to the activities on the critical path. You need to look for any activity with a low float. And don’t forget that there may be some activities that aren’t on the critical path but still have a float of zero! These are the ones where you really want to pay attention and watch out for potential resource problems.

Figure 6-67.  

All of the processes in Project Schedule Management tie together! When you develop your schedule, you’re using the durations for your activities that you came up with in Estimate Activity Durations.

Figure out the early start and early finish

Coming up with the float for each activity is useful, but you can actually do better! When you have a long critical path, but the other paths in your network diagram are short, then you have a lot of freedom in when you can start and finish each of the activities that are not on the critical path. You can use early start and early finish to get a handle on exactly how much freedom you have in your schedule.

Figure 6-68.  

Early start

Is the earliest time that an activity can start. An activity near the end of the path will only start early if all of the previous activities in the path also started early. If one of the previous activities in the path slips, that will push it out.

Early finish

Is the earliest time that an activity can finish. It’s the date that an activity will finish if all of the previous activities started early and none of them slipped.

When you find the early start and early finish for each task, you know exactly how much freedom you have to move the start dates for those activities around without causing problems.

Figure out the latest possible start and finish

It’s also important to know how late any activity can run before it delays the project. That’s what late start and late finish are for! They let you figure out how late you can start a certain task and how much it can slip before it delays your project.

Figure 6-69.  

Late start

Is the latest time that an activity can start. If an activity is on a path that’s much shorter than the critical path, then it can start very late without delaying the project—but those delays will add up quickly if other activities on its path also slip!

Late finish

Is the latest time that an activity can finish. If an activity is on a short path and all of the other activities on that path start and finish early, then it can finish very late without causing the project to be late.

Figuring out the late start and late finish will help you see how much “play” you have in your schedule. An activity with a large late start or late finish means you have more options.

Add early and late durations to your diagrams

You can use a method called forward pass to add the early start and finish to each path in your network diagram. Once you’ve done that, you can use backward pass to add the late start and finish. It makes your network diagrams look a little more complicated, but it gives you a lot of valuable information.

Figure 6-70.  

Take a forward pass through the network diagram. Start at the beginning of the critical path and move forward through each activity. Follow these three steps to figure out the early start and early finish!

Figure 6-71.  

1. The ES (early start) of the first activity in the path is 1. The EF (early finish) of any task is its ES plus its duration minus 1. So start with Activity A. It’s the first in the path, so ES = 1, and EF = 1 + 6 – 1 = 6.

2. Now move forward to the next activity in the path, which is Activity B in this diagram. To figure out ES, take the EF of the previous task and add 1. So for Activity B, you can calculate ES = 6 + 1 = 7, and EF = 7 + 5 – 1 = 11.

3. Uh-oh! Activity C has two predecessors. Which one do you use to calculate EF? Since C can’t start until both B and D are done, use the one with the latest EF. That means you need to figure out the EF of Activity D (its ES is 1, so its EF is 1 + 2 – 1 = 2). Now you can move forward to Activity C and calculate its EF. The EF of Activity D is 2, which is smaller than B’s EF of 11, so for Activity C the ES = 11 + 1 = 12, and EF = 12 + 7 – 1 = 18.

Take a backward pass to find late start and finish

You can use a backward pass through the same network diagram to figure out the late finish and start for each activity.

The backward pass is just as easy as the forward pass. Start at the end of the path you just took a pass through and work your way backward to figure out the late start and finish.

Figure 6-72.  

Start with the critical path. You’re calculating the latest any activity can start and finish, so it makes sense that you need to start at the end of the project and work backward—and the last activity on the critical path is always the last one in the project. Then do these three steps, working backward to the next longest path, then the next longest, and so on, until you’ve filled in the LS and LF for all of the activities. Fill in the LF and LS for the activities on each path, but don’t replace any LF or LS you’ve already calculated.

1. Start at the end of the path, with Activity C. The LF (late finish) of the last activity is the same as the EF. Calculate its LS (late start) by subtracting its duration from the LF and adding 1. LS = 18 – 7 + 1 = 12.

2. Now move backward to the previous activity in the path—in this case, Activity B. Its LF is the LS of Activity C minus 1, so LF = 12 – 1 = 11. Calculate its LS in the same way as step 1: LS = 11 – 5 + 1 = 7.

3. Now do the same for Activity A. LF is the LS for Activity B minus 1, so LF = 7 – 1 = 6. And LS is LF minus duration plus 1, so LF = 6 – 6 + 1 = 1.

4. Now you can move onto the next longest path, Start-D-C-Finish. If there were more paths, you’d then move on to the next longest one, and so on, filling in LF and LS for any nodes that haven’t already been filled in.

Figure 6-73.  

When a task is a predecessor to two later tasks, use the one with the lower LS to calculate its LF.

Let’s take some time out to walk through this!

All of this critical path stuff seems pretty serious, right? It seems like one of the toughest concepts on the exam...at first! But don’t sweat it, because it’s actually not hard—it just takes a little practice. Once you do it yourself, you’ll see that there’s really nothing to worry about.

Note

Calculating the ES, EF, LS, and LF may seem complicated, but it only takes a little practice to get the hang of it. Once you walk through it step by step, you’ll see that it’s actually pretty easy!

Sharpen your pencil

There are four paths in this network diagram. Fill in the activity names and durations for each of the paths.

Figure 6-74.  

We’re not done yet! There’s more on the next page...

Sharpen your pencil

Take a forward pass through each of the four paths in the diagram and fill in the early starts and early finishes for each activity. Start with the first one.

Figure 6-75.  

Let’s move on to the second path.

Figure 6-76.  

The next path isn’t as straightforward as it looks. Start by filling in its values.

Figure 6-77.  

Now take another look at it, and how it mixes with the last path. It includes Activity H, which was also in the last path. H will have a different ES depending on which path you use! So which predecessor do you use: E or G? The idea here is that you use the predecessor with the larger EF value when you calculate the ES for activity H (because you want the latest possible start date).

Figure 6-78.  

You’ve calculated the ES for each activity. Use that information and take a backward pass through the paths, starting with the first two paths.

First start with the critical path. Take the EF of the last activity in the critical path and use it as the LF for the last activity in every path. If you take a minute to think about it, it makes sense to do that. The point of LF is to figure out the absolute latest that the activity can end without making the project late. And as long as every non-critical-path activity ends before the last activity in the critical path, then it won’t be late.

We’ll start by giving you the LF of critical path, Start-D-E-H-Finish, which is 17.

Figure 6-79.  

Finish up by calculating the LS and LF for the last two paths!

Activities B and D have two possible choices for which LS to use for the calculation. For Activity B, do you use the LS of C or the LS of F? And for Activity D, do you use Activity E or G? The answer is that you always use the lowest value of LS to calculate the LF. The reason is that you’re trying to find the latest possible start date that won’t make the project late. If you use an activity with a later LS, and the activity really is delayed by that much, then it’ll cause a delay in both following activities. And that will make the one with the lower LS start too late.

Figure 6-80.  

Sharpen your pencil Solution

For the exam, you’ll only have to do one or two of these calculations, not a whole string of them like this. You’ll definitely be able to handle the exam questions now!

Note

If you got a few of these wrong, don’t worry. It’s easy to miss one calculation, and that leads to a problem on the whole path.

Figure 6-81.  

You won’t have to do this kind of thing on the job…that’s what computers are for!

Project management software like Microsoft Project will do these calculations for you. But you need to know how to do it yourself, because when the computer is doing critical path analysis, this is exactly how it figures it out!

Figure 6-82.  

there are no Dumb Questions

Q: Would I really use this critical path stuff in real life, or is it just something I need to memorize for the PMP exam?

A: Yes, critical path analysis really is important in real life! Sure, for a small project with a dozen or so activities, it’s pretty easy to figure out which activities are critical and which can slip by a little bit. But what happens if you’ve got a project with dozens of team members and hundreds of activities? That’s where critical path analysis can come in very handy. For a project like that, you’d probably be using project management software rather than calculating the critical path yourself, and the software will be able to highlight that path for you. Pay special attention to all of the activities that are on the critical path—those are the ones that could potentially delay the project.

Q: What about the other numbers? How do I use float?

A: Float is a very powerful planning tool that you can use to figure out how well your project is going, and to predict where your trouble spots might be. Any activity with a low or zero float absolutely must come in on time, while the people performing an activity with a larger float have more freedom to slip without delaying the project. So you might want to assign your “superstar” resources to the low-float activities, and those people who need a little more mentoring to the ones with higher float.

Q: OK, but what about late start, early finish, and those other numbers? Do those do me any good?

A: Early and late start and finish numbers are also very useful. How many times have you been in a situation where you’ve been asked, “If we absolutely had to have this in two months, can we do it?” Or, “How late can this project realistically be?” Now you can use these numbers to give you real answers, with actual evidence to back them up.

Here’s an example. Let’s say you’ve got an activity in the middle of your project, and one of your team members wants to plan a vacation right at the time that the activity will start. Do you need to find someone to fill in for him? If he’ll be back before the late start date, then your project won’t be late! But that comes at a cost—you’ll have used up the extra slack in the schedule.

Q: I can see how the critical path is useful on its own, but what does it have to do with the rest of Project Schedule Management?

A: If you start putting together your schedule but the activities are in the wrong order, that’s really going to cause serious problems…and sometimes doing critical path analysis is the only way you’ll really figure out that you’ve made that particular mistake. That’s why you need to pay a lot of attention to the Sequence Activities tools and techniques. If you’ve come up with an inefficient or inaccurate sequence, with too many or incorrect predecessors and dependencies, then your entire critical path analysis will be useless.

Bullet Points: Aiming for the Exam

• The critical path is the path that has the longest duration.

• You should be able to figure out the number of paths in a project network diagram, and the duration of each path.

• The float for an activity is the amount that its duration can slip without causing the project to be delayed. The float for any activity on the critical path is zero.

• You’ll need to know how to calculate the early start, late start, early finish, and late finish for an activity in a network diagram using the forward pass and backward pass. This is the core of critical path analysis.

• You may see a PDM (or activity-on-node) diagram with special nodes that have extra boxes in the corners for the ES, EF, LF, and LS.

• Don’t forget that when two paths intersect, you have to decide which ES or LF value to take for the calculation in the next node. For the forward pass, use the larger value; for the backward pass, use the smaller one.

Crash the schedule

There are two important schedule compression techniques that you can use to bring in your project’s milestone dates…but each has its own cost. When you absolutely have to meet the date and you are running behind, you can sometimes find ways to do activities more quickly by adding more resources to critical path tasks. That’s called crashing.

Figure 6-83.  

Figure 6-84.  

Crashing the schedule means adding resources or moving them around to shorten it. Crashing ALWAYS costs more and doesn’t always work!

Then you can’t crash the schedule.

There’s no way to crash a schedule without raising the overall cost of the project. So, if the budget is fixed and you don’t have any extra money to spend, you can’t use this technique.

Figure 6-85.  

Fast-tracking the project

Another schedule compression technique is called fast-tracking. Sometimes you’ve got two activities planned to occur in sequence, but you can actually do them at the same time. On a software project, you might do both your user acceptance testing and your functional testing at the same time, for example. This is pretty risky, though. There’s a good chance you will need to redo some of the work you have done concurrently.

Note

On the exam, if you see something about “overlapping activities,” it’s talking about fast-tracking.

Figure 6-86.  

Crashing and fast-tracking are SCHEDULE COMPRESSION tools.

Exercise

Each of these scenarios describes a schedule compression technique. Pick which are examples of fast-tracking and which are crashing.

1. Kathleen guesses that 70% of the invitees will RSVP. Instead of waiting for all of them to come in, she goes ahead and reserves the tables and chairs now.

   Fast-tracking

   Crashing

2. Rebecca is taking a really long time to choose the decorations, so Kathleen brings in a professional decorator to help, even though it will cost more.

   Fast-tracking

   Crashing

3. Kathleen needs to get the invitations out quickly, so she hires two temps to come in and help her stuff envelopes for a few days.

   Fast-tracking

   Crashing

Answers in “ Exercise Solution”.

Use data analysis techniques when you build your schedule

Figure 6-87.  

It’s always a good idea to think about all of the things that could go wrong on your project in advance. Trying to think through all of the possible problems your project could run into is called what-if analysis.

• What if the limo breaks down?

• What if the florist cancels at the last minute?

• What if the dress doesn’t fit?

• What if the band gets sick?

• What if the guests get food poisoning?

• What if there’s a typo in the church address on the invitation?

• What if the bridesmaids don’t show up?

• What if the cake tastes horrible?

• What if we lose the rings?

Figure 6-88.  

That way, you can figure out how to deal with any problems that might come your way. Sometimes there’s no way to still meet your dates and deal with these scenarios. But it always makes sense to try to understand the impact they will have on your schedule.

Simulation

This is a specific kind of what-if analysis where you model uncertainty using a computer. There are some packages that will help to calculate risk using random numbers and Monte Carlo analysis algorithms. While this is not a commonly used technique, there might be a question or two about it on the PMP exam, and you should know what it is.

Figure 6-89.  

Scheduling tool

Using a project management software package to create a model of the schedule and adjusting various elements to see what might happen is another technique for analyzing network diagrams.

Figure 6-90.  

Other Develop Schedule tools and techniques

There are just a few more tools and techniques in the Develop Schedule process that you should know.

Resource optimization techniques

Sometimes only one resource can do a given activity. If that resource is busy doing another activity on the critical path, the path itself needs to change to include that dependency. That’s the point of resource leveling. It evaluates all of the resources to see if the critical path needs to change to accommodate resource assignments.

Figure 6-91.  

Adjusting leads and lags

If you made any mistakes in your leads and your lags, you might be able to adjust them to change the projected end date.

Figure 6-92.  

Data analysis: schedule compression and schedule network analysis

The last two tools and techniques in the Develop Schedule process are the ones you just learned over the last few pages: schedule compression and schedule network analysis using critical path, float, and the other schedule analysis techniques you just learned.

Figure 6-93.  

Agile release planning

Agile teams typically have a cadence or timebox they use to develop. An Agile release plan takes the list of user stories that have been estimated for a release and uses their estimated size of effort to map them to an upcoming iteration. By presenting the release plan in this way, the team gives the product owner the ability to reprioritize stories and change the order in which stories will be released.

Project management information system

Your company might have scheduling software that they use to generate schedules. You might also use a project management information system to reference existing company calendar information that might impact your schedule.

Outputs of Develop Schedule

Of course, the main product of Develop Schedule is the schedule. But there are a few other supporting documents that help you understand how the work will get done as well.

Figure 6-94.  

Project schedule

All of that analysis and modeling should produce a schedule that everyone can get behind. After thinking your way through everything that can go wrong and assigning resources, you should have a pretty accurate prediction of the work required to complete the project.

Figure 6-95.  

Change requests

These are the same change requests that you’ve seen in other processes. They should be really familiar by now!

Figure 6-96.  

Project calendars

Calendars will help you keep track of the time when team members will be away on vacation or unavailable to work on your project.

Figure 6-97.  

Schedule data

The schedule data is a collection of information about your schedule. It will include things that you’ll need to analyze your schedule later on in the project: alternative schedules, specific requirements for resources, milestone charts, bar charts, project schedule network diagrams, and other data and metrics about your schedule.

Figure 6-98.  

Before you can do change control, you need requested changes. Once the change is approved, you can update the baseline.

Figure 6-99.  

Schedule baseline

When the Develop Schedule process is complete, a baseline is created so that actual progress can be compared to the plan.

Project Management plan updates

Since the schedule baseline and Schedule Management plan are both part of the Project Management plan, it makes sense that it would have to be updated.

Figure 6-100.  

Project documents updates

While you’re creating the schedule, you might find that you need to update calendars, your resource requirements, the attributes of the activities themselves, or even your risk register, to name a few possibilities.

Figure 6-101.  

What’s my Purpose

For the exam, you need to know Develop Schedule outputs. Several outputs from the wedding’s Develop Schedule process are on the left. Match them to the correct description on the right.

Project schedule Schedule data Schedule baseline Project calendars Project document updates

Kathleen gives a list of dates to the caterer telling him when he will need to have his menu plans, and when the shopping for the ingredients will need to be complete for the reception and rehearsal dinner. Kathleen realizes that she needs to make a change to how she keeps track of the waiters’ time, so she makes a change to the document that describes it. While making the schedule, Kathleen realizes that the catering company can’t work from 3 to 4 on the day of the event because they’ll be traveling from another event. Kathleen makes a copy of the schedule when it’s done so that she can compare how she is doing to the original plan. There’s a big poster on the wall where Kathleen keeps track of who does what, and when.

Answers: A– 5; B –1; C– 4; D–3; E–2

there are no Dumb Questions

Q: Don’t we need to go through change control before we update the resource requirements or the activity attributes?

A: No. You need to go through change control if you are requesting changes to, say, your Cost Management plan. But while you are working on creating your schedule, everything you have created as part of the Project Schedule Management knowledge area is fair game.

As you work your way through your network diagram and figure out new dependencies, you will find that you need more resources for some items or that the activity itself has changed. That’s why this process gives you the freedom to refine your earlier idea and make all of the Project Schedule Management documents sync with your new understanding.

The Develop Schedule process is about taking all of the information you can think of up front and putting it into a schedule that is realistic. When you are done with this process, you should have a really good idea of what you are going to do, who will do it, and how long it will take.

Q: We always want to do our projects as quickly as we can. Why don’t we always fast-track and crash our schedules?

A: Because crashing is expensive and fast-tracking is risky. While it may look good on paper to add a lot of resources to a project that is running late, it often adds so much management overhead and training issues that the project just comes in later.

Even though it might seem like some predecessors are really unnecessary, you usually planned them for a reason. So when you break your dependencies to fast-track your project, you can significantly compromise the quality of the work that gets done. That means you might have to redo it altogether—which would probably take a lot of time.

While fast-tracking and crashing might work sometimes, they always add both risk and cost to your project.

Q: Do people really do Monte Carlo analysis to figure out their schedules? I have never heard of that before.

A: It’s true that most people don’t use this technique to figure out what might go wrong on their projects, so don’t feel bad if you’ve never heard of it. Some people think that this is just one of those things that is on the PMP exam, so you have to know what it is. But there really are some project managers who use it and get great results!

Updates refine the outputs of previous processes so you don’t have to go back and redo them.

Influence the factors that cause change

Note

You might get a question on the PMP exam that asks you about this.

Kathleen doesn’t just sit around and wait for schedule changes to happen…

Figure 6-102.  

Joe (on phone): Good afternoon, Joe’s Catering. Joe speaking. How can I help you?

Kathleen: Hello, Joe. This is Kathleen calling about Rob and Rebecca’s wedding.

Joe: Oh, hi! Everything’s going fine with that wedding.

Kathleen: Are you sure? What about that big convention across town that’s going to be happening at the same time? Won’t it be tough to find waiters in June?

Note

By realizing that the convention across town will need waiters, too, Kathleen prevents a lot of changes before they cause schedule problems!

Joe: I didn’t think of that; we’d better start figuring out how we’ll handle it now.

The project manager doesn’t just wait for change to happen! She finds the things that cause change and influences them.

Control Schedule inputs and outputs

As the project work is happening, you can always discover new information that makes you reevaluate your plan, and use the Control Schedule process to make the changes. The inputs to Control Schedule cover the various ways you can discover that information. The outputs are the changes themselves.

Figure 6-103.  

Figure 6-104.  

What Control Schedule updates

All of the documents you made during the Develop Schedule process get updated during the Control Schedule process. Here’s a closer look at what those updates mean.

Figure 6-105.  

As your project is happening, you might need to revise your list of assumptions to include new information about activity sequencing or duration.

Figure 6-106.  

You may add supporting details to estimates—like assumptions that were made—to help people understand how the team came up with the estimate. As you make changes to your project schedule, you should be tracking your lessons learned so that other projects can benefit from your experience. Sometimes you might find changes to your basis of estimates as your project progresses.

Figure 6-107.  

Throughout your project, you’ll update the project schedule with any new information you learn as you execute your plan.

Figure 6-108.  

Changes to resource calendars and risks need to be updated as you go. You might find that resources who originally planned to be on vacation end up changing their plans, or you might identify new risks as you go.

Figure 6-109.  

Schedule data is information about the schedule, like start date, end date, and information about the critical path. In some cases, things change so drastically while your project is executing that you need to create new activities and forecasted duration dates to get an accurate picture of your schedule.

Figure 6-110.  

Managing schedule change means keeping all of your project documents up to date.

Measuring and reporting performance

Most often, you identify changes by looking at performance data. It’s just as important once you make a change to gather performance data as it was when you found the change in the first place. Here’s how performance data feeds into the Control Schedule process.

The Control Schedule process turns work performance data into work performance information.

Figure 6-111.  

Control Schedule tools and techniques

The tools and techniques for Control Schedule are all about figuring out where your project schedule stands. By comparing your actual project to the schedule you laid out in the baseline and looking at how people are performing, you can figure out how to handle every schedule change.

Figure 6-112.  

Data analysis

In this process you use data analysis to evaluate the information coming in from the project to forecast whether or not your team is going to meet its forecasted dates. There are two important calculations called schedule variance (SV) and schedule performance index (SPI) that give you valuable information about how your project is doing. Those two calculations are part of the earned value technique, which you’ll learn all about in the next chapter.

Agile teams often use iteration burndown charts to gauge whether they are ahead or behind on work they’ve committed to accomplishing within a given timeboxed iteration.

Performance reviews are used to compare actual dates versus the dates in the schedule baseline. Trend analysis lets you see if performance of the team is getting better or worse over time. Variance analysis is when you dig in and try to understand the cause of the variance between actual dates and the dates in the baseline. What-if scenario analysis allows you to model possible schedule changes to mitigate risks or respond to changes.

Leads and lags, and schedule compression

Most of the tools from the last process apply to this one too. As you find variances in the schedule, you need to figure out the impact of those issues and change your schedule to account for the new information.

Resource optimization

As things change in your project, you need to make sure that resources are covering all of the activities in your plan. That means you need to distribute resources so that the work that needs to get done always has a resource available to do it.

Figure 6-113.  

Critical path method

Use the precedence diagramming method to figure out your early start and late finish for all of the tasks in your project. Then calculate the float to find which tasks are in the critical path. Once you know the critical path, you can choose to fast-track or crash the schedule to optimize the amount of time your project will take.

Project management information system

This is software like Microsoft Project that helps you organize and analyze all of the information you need to evaluate the schedule of any project.

there are no Dumb Questions

Q: When I create work performance information, who uses it?

A: The work performance information that you create is used by a lot of people. The team uses it to keep an eye on the project. If there’s a schedule problem coming up, it alerts the team so that they can help you figure out how to avoid it.

Performance information is also used by your project’s sponsor and stakeholders, who are very interested in whether or not your project is on track. That information gives them a good picture of how the project is doing…and that’s especially important in Control Schedule, because most change control systems require that every change is approved by a change control board that includes sponsors and stakeholders.

Q: What’s schedule data used for?

A: You use the schedule data to build the schedule, and you’ll usually generate and analyze it using a schedule tool (like Microsoft Project). It includes detailed information about things like resource requirements, alternate best-case and worst-case schedules, and contingency reserves.

When you put together your schedule, you should look at all of these things in order to create an accurate plan. The more information you have when you’re building your schedule, the more likely it is that you’ll catch those little problems that add up to big schedule slips.

Q: One of the tools is project management software. Do I need to know how to use software in order to pass the exam?

A: No. The PMP exam does not require that you know how to use software like Microsoft Project. However, if you spend a lot of time using project management software, then you probably have become very familiar with a lot of the Project Schedule Management concepts. It’s a good way to learn the basics of schedule management.

Q: How often am I supposed to update the project calendar?

A: The project calendar shows you the working days for your team, holidays, nonworking days, planned training, and the dates that could affect your project. Luckily, in most companies these dates don’t change very often. You probably won’t need to update it—and most project managers just use their company’s existing project calendar.

When you’re doing Develop Schedule, you may discover that you need to make a change to the project calendar. That’s why updates to the project calendar are an output of Develop Schedule.

Q: What do I do with work performance data and work performance information once I’ve collected it?

A: When you’re planning your project, you’ll often look to your company’s past projects to see what went well and what could have been planned better. And where do you look? That information is in the organizational process assets.

So where do you think that information comes from? It comes from project managers like you who added their work performance data and information to the company’s organizational process asset library.

Any time you generate data about your project, you should add it to your organizational process assets so you can use it for future projects.

Control Schedule Magnets

You’ll see change control over and over again—every single knowledge area has its own change control process! Luckily, you’ll start to see how similar they all are. But Control Schedule has its own quirks, and they’re important for understanding Project Schedule Management.

Figure 6-114.  

Figure 6-115.  

Answers in “Control Schedule Magnets Answers”.

Schedulecross

Take some time to sit back and give your right brain something to do. It’s your standard crossword; all of the solution words are from this chapter.

Figure 6-116.  

Across

1. Taking work packages from the WBS and breaking them down into activities.

5. The “P” in PDM.

7. The kind of analysis where you ask a lot of questions about possibilities.

8. A snapshot of the schedule that you can use for later comparison.

10. __________ estimation means plugging data about your project into a database of historical information to get an estimate of how long it will take to do the work.

12. Giving a successor task some time to start before a predecessor finishes.

13. Adding more resources to a project so you can get it done faster is called _______ the schedule.

14. A PERT three-point estimate is optimistic time + 4 × most likely time + _______ time and divided by 6.

Down

2. Any delay in an activity on the _______ path will delay the entire project.

3. You do this sort of planning when you get more information as the project progresses.

4. What you’re doing to resources when you evaluate all of them to see if the critical path needs to change to accommodate their restrictions.

6. An activity with a dependency on something outside the project has an _________ predecessor.

9. ________ Activities is the process where you put the activities in order.

11. How long an activity can slip before the whole project is delayed.

Answers in “ Schedulecross Solution”

Key Concept Review

Understanding how long it will take to do the work within your project is a core part of the job. Project Schedule Management is how you come to understand the way your work stacks up once you figure in the order you’ll use to do it and how long each thing your team needs to do will take.

KEY CONCEPTS

We’ve talked about the processes you and your team will use when identifying and managing the schedule, but it’s worth taking a minute to think about how your approach to schedule management affects the overall project.

Figure 6-117.  

• The main product of the Project Schedule Management processes is a detailed plan. Your plan will make the timeline for your project clear and will show your stakeholders how your team plans to meet its goal and how long each step they’ve identified will take.

• Most teams use scheduling software to figure out their planned dates once they’ve spent some time nailing down the list of activities they’ll do and the estimated durations for those activities.

• Some teams who are working on projects with smaller scope and more near-term deadlines think of their entire scheduling process as one step. They figure out all of the activities they’ll need to accomplish, the sequence they’ll do them in, and their durations all in one estimation session.

• Since changes across all of the knowledge areas often affect the project timelines, the schedule should be flexible and updated frequently.

SCHEDULE MANAGEMENT IS ABOUT GETTING A HANDLE ON HOW THE TEAM WILL WORK AND WHEN THE PROJECT WILL BE DELIVERED.

TRENDS

Here are a few trends in Schedule Management that might help you to improve and manage the timeline for your projects more effectively.

• Iterative scheduling uses a backlog of requirements or user stories, and pulls items from that backlog into timeboxed iterations as a means of sequencing work at the last responsible moment. Agile teams use this technique to avoid determining all of their dependencies up front. This gives them the freedom to adapt to change without resetting detailed schedule expectations.

• On-demand scheduling is similar because it focuses on pulling work from a backlog and completing it as soon as possible. The main difference between this technique and iterative scheduling is that it doesn’t rely on predetermined timeboxed iterations to forecast an end date. Instead, items are delivered as they are completed.

TAILORING

When you make changes to the processes your team will use during the course of your project, there are a few considerations, that might influence your decisions:

Figure 6-118.  

• What development lifecycle will your project follow? Should you focus on building a detailed schedule up front, or will you define iteration timeboxes, prioritize the work, and let the team deliver in priority order?

• Do you know if there are resources who won’t be available for specific timeframes and if that will affect your schedule?

• Is your project innovative or highly uncertain? How will you know if your project plan is focused on reducing uncertainty as it progresses? How will you track your progress on the project?

• If your project is dependent on a tool or technology, will you be able to use that tool easily?

AGILE CONSIDERATIONS

Agile teams focus on team collaboration around commitments and making decisions at the last responsible moment. They use short iterations to create feedback loops that let them change the activities they’ll do and their sequence when new information arises. Agile teams use timeboxes and an understanding of the rate at which work is accomplished (velocity) to give a sense of when items will be completed, but always leave the option to change the approach to delivering products when priorities change.

Another satisfied customer!

Rob and Rebecca had a beautiful wedding! Everything was perfect. The guests were served their meals, the band was just right, and everyone had a blast…

Figure 6-119.  

Exercise Solution

Each of these scenarios describes a different tool or technique from Estimate Activity Durations. Write down which tool or technique is being described.

1. Kathleen comes up with three estimates (one where everything goes wrong, one where some things go wrong, and one where nothing goes wrong) for printing invitations, and averages them together to come up with a final number. Three-point estimate

2. There will be two different catering companies at the wedding. Kathleen asks the head chef at each of them to give her an estimate of how long it will take to do the job. Expert judgment

3. There’s a spreadsheet Kathleen always uses to figure out how long it takes guests to RSVP. She enters the number of guests and their zip codes, and it calculates an estimate for her. Parametric estimating

4. Kathleen’s done four weddings that are very similar to Rob and Rebecca’s, and in all four of them it took exactly the same amount of time for the caterers to set up the reception hall. Analogous estimating

Exercise Solution

Here are some examples of three point estimates. Use the formula to figure out the expected time for each of these.

1. Expected duration = 50d; Optimistic duration = 30d; Most likely duration = 45d; Pessimistic duration = 90d

2. Expected duration = 20.3d; Optimistic duration = 12d; Most likely duration = 20d; Pessimistic duration = 30d

3. Expected duration = 25d; Optimistic duration = 10d; Most likely duration = 25d; Pessimistic duration = 40d

4. Expected duration = 51.8d; Optimistic duartion = 33d; Most likely duration = 49d; Pessimistic duration = 82d

Exercise Solution

You may get questions on the exam asking you to identify the critical path in a network diagram. You had to practice that by finding the critical path and duration for this PDM.

Figure 6-120.  

Exercise Solution

You’ll need to be able to calculate the float of an activity in a network diagram for the exam. Take another look at this PDM from the last exercise. Can you calculate the float for each activity?

Figure 6-121.  

Exercise Solution

Each of these scenarios describes a schedule compression technique. Pick which are examples of fast-tracking and which are crashing.

1. Kathleen guesses that 70% of the invitees will RSVP. Instead of waiting for all of them to come in, she goes ahead and reserves the tables and chairs now.

   Fast-tracking

   Crashing

2. Rebecca is taking a really long time to choose the decorations, so Kathleen brings in a professional decorator to help, even though it will cost more.

   Fast-tracking

   Crashing

3. Kathleen needs to get the invitations out quickly, so she hires two temps to come in and help her stuff envelopes for a few days.

   Fast-tracking

   Crashing

Sharpen your pencil Solution

You’ll need to know how to turn a table of nodes into a network diagram, so here’s your chance to get some practice! Here’s a list of nodes for a PDM network diagram. Try drawing the diagram based on it:

Figure 6-122.  

Now try another one!

Figure 6-123.  

Control Schedule Magnets Answers

You’ll see change control over and over again—every single knowledge area has its own change control process! Luckily, you’ll start to see how similar they all are. But Control Schedule has its own quirks, and they’re important for understanding Project Schedule Management.

Figure 6-124.  

Figure 6-125.  

Schedulecross Solution

Figure 6-126.  

Exercise Solution

Here are some examples of three-point estimates. Use the formula to figure out the expected time for each of these.

1. Expected duration = 50d; Optimistic duration = 30d; Most likely duration = 45d; Pessimistic duration = 90d

2. Expected duration = 20.3d; Optimistic duration = 12d; Most likely duration = 20d; Pessimistic duration = 30d

3. Expected duration = 25d; Optimistic duration = 10d; Most likely duration = 25d; Pessimistic duration = 40d

4. Expected duration = 51.8d; Optimistic duration = 33d; Most likely duration = 49d; Pessimistic duration = 82d

Exam Questions

1. You’re managing a project when your client tells you that an external problem happened, and now you have to meet an earlier deadline. Your supervisor heard that in a situation like this, you can use schedule compression by either crashing or fast-tracking the schedule, but he’s not sure which is which. What do you tell him?

   1. Crashing the project adds risk, while fast-tracking adds cost.

   2. When you crash a project, it always shortens the total duration of the project.

   3. Crashing the project adds cost, while fast-tracking adds risk.

   4. When you fast-track a project, it always shortens the total duration of the project.

2. Given this portion of the network diagram to the right, what’s the EF of activity F?

   1. 41

   2. 49

   3. 53

   4. 61

3. Given this portion of the network diagram to the right, what’s the LS of activity F?

   1. 41

   2. 49

   3. 53

   4. 61

   

   Figure 6-127.  

4. You are managing a software project. Your QA manager tells you that you need to plan to have her team start their test planning activity so that it finishes just before testing begins. But other than that, she says it can start as late in the project as necessary. What’s the relationship between the test planning activity and the testing activity?

   1. Start-to-Start (SS)

   2. Start-to-Finish (SF)

   3. Finish-to-Start (FS)

   4. Finish-to-Finish (FF)

5. You’re managing an industrial design project. You’ve come up with the complete activity list, created network diagrams, assigned resources to each activity, and estimated their durations. What’s the next thing that you do?

   1. Use rolling wave planning to compensate for the fact that you don’t have complete information.

   2. Create the schedule.

   3. Consult the project scope statement and perform Sequence Activities.

   4. Use fast-tracking to reduce the total duration.

6. Which of the following is NOT an input to Develop Schedule?

   1. Activity list

   2. Project schedule network diagrams

   3. Resource calendars

   4. Schedule baseline

7. Three members of your project team want to pad their estimates because they believe there are certain risks that might materialize. What is the BEST way to handle this situation?

   1. Estimate the activities honestly, and then use a contingency reserve to cover any unexpected costs.

   2. Allow more time for the work by adding a buffer to every activity in the schedule.

   3. Tell the team members not to worry about it, and if the schedule is wrong it’s OK for the project to be late.

   4. Crash the schedule.

8. You’re managing a software project. You’ve created the schedule, and you need to figure out which activities cannot slip. You’ve done critical path analysis, identifying the critical path and calculating the early start and early finish for each activity. Which activities cannot slip without making the project late?

   1. The ones with the biggest difference between ES and LF

   2. The activities on the critical path

   3. The activity with the most lag

   4. The last activity in the project, because it has no float

9. What is the critical path in the activity list to the right?

   1. Start-A-B-C-Finish

   2. Start-A-D-E-F-Finish

   3. Start-G-H-I-J-Finish

   4. Start-A-B-J-Finish

   Name	Predecessor	Duration
   Start	—	—
   A	Start	6
   B	A	4
   C	B	8
   D	A	1
   E	D	1
   F	E	2
   G	Start	3
   H	G	3
   I	H	2
   J	B, I	3
   Finish	F, J, C	—

10. What is the float for activity F in the activity list to the right?

    1. 0

    2. 7

    3. 8

    4. 10

11. You’re managing an interior decoration project when you find out that you need to get it done earlier than originally planned. You decide to fast-track the project. This means:

    1. Starting the project sooner and working overtime

    2. Assigning more people to the tasks at a greater total cost, especially for activities on the critical path

    3. Starting activities earlier and overlapping them more, which will cost more and could add risks

    4. Shortening the durations of the activities and asking people to work overtime to accommodate that

12. Slack is a synonym for:

    1. Float

    2. Lag

    3. Buffer

    4. Reserve

13. You’re managing a construction project. You’ve decomposed work packages into activities, and your client needs a duration estimate for each activity that you come up with. Which of the following will you use for this?

    1. Milestone list

    2. Activity list

    3. Critical path analysis

    4. Project schedule network diagram

14. What’s the correct order of the Project Schedule Management planning processes?

    1. Sequence Activities, Define Activities, Estimate Activity Durations, Develop Schedule

    2. Plan Schedule Management, Define Activities, Sequence Activities, Develop Schedule, Estimate Activity Durations

    3. Plan Schedule Management, Define Activities, Sequence Activities, Estimate Activity Durations, Develop Schedule

    4. Plan Schedule Management, Develop Schedule, Define Activities, Sequence Activities, Estimate Activity Durations

15. Which of the following is NOT a tool or technique used in Estimate Activity Durations?

    1. SWAG estimation

    2. Parametric estimation

    3. Analogous estimation

    4. Three-point estimation

16. You’re managing a project to build a new project management information system. You work with the team to come up with an estimate of 27 weeks. In the best case, this could be shortened by two weeks because you can reuse a previous component. But there’s a risk that a vendor delay could cause the project to be delayed by five weeks. Use PERT to calculate a three-point estimate for this project.

    1. 25.83 weeks

    2. 26 weeks

    3. 27.5 weeks

    4. 28.3 weeks

17. Given the network diagram below, what’s the critical path?

    1. Start-A-B-C-End

    2. Start-A-D-G-End

    3. Start-E-D-C-End

    4. Start-E-F-G-End

18. For that same network diagram below, what’s the float for activity A?

    1. 0 weeks

    2. 1 week

    3. 2 weeks

    4. 4 weeks

19. For that same network diagram below, what’s the float for activity E?

    1. 0 weeks

    2. 1 week

    3. 2 weeks

    4. 4 weeks

    

    Figure 6-128.  

20. You’re managing a software project when your customer informs you that a schedule change is necessary. Which is the BEST thing to do?

    1. Consult the schedule management plan.

    2. Notify the team and the sponsor that there’s going to be a schedule change.

    3. Influence the factors that cause change.

    4. Refuse to make the change because there’s already a schedule baseline.

21. Your company has previously run other projects similar to the one you’re currently managing. What is the BEST way to use that information?

    1. Check the organizational process assets for lessons learned and other information about the past projects.

    2. Use parametric estimation to estimate your project based on past projects’ performance.

    3. Start from scratch because you don’t want mistakes from past projects to influence you.

    4. Reuse the Project Management plan from a past project.

22. You’re planning the schedule for a highway construction project, but the final date you came up with will run into the next budget year. The state comes up with capital from a reserve fund, and now you can increase the budget for your resources. What’s the BEST way to compress the schedule?

    1. Go back to your three-point estimates and use the most optimistic ones.

    2. Use the extra budget to increase your contingency reserve.

    3. Hire more experts to use expert judgment so your estimates are more accurate.

    4. Crash the schedule.

23. You’re managing a construction project. You’ve decomposed work packages into activities, and your client needs a duration estimate for each activity that you came up with. Which of the following BEST describes what you are doing?

    1. Evaluating each activity to figure out how much effort it will take

    2. Estimating the number of person-hours that will be required for each activity

    3. Understanding, in calendar time, how long each activity will take

    4. Estimating how many people it will take to perform each activity

Exam Answers

1. Answer: C

   You’re likely to get some questions that ask you about crashing and fast-tracking, and it’s important to know the difference between them. When you crash the project, it means that you add resources to it, especially to the critical path. There’s no real risk in doing that—in the worst-case scenario, the extra people just sit around!—but it does cost more. Fast-tracking means adjusting the schedule so that activities overlap. The same resources are doing the work, so it’s not going to cost more, but it’s definitely riskier, because now you’ve eliminated buffers and possibly broken some dependencies! And remember that crashing or fast-tracking won’t always work to make the project go faster!

2. Answer: C

   To calculate EF for a task with two predecessors, start by calculating the ES: choose the highest EF of the predecessors and add 1: ES = 40 + 1 = 41. Then use that ES to calculate EF by adding the duration and subtracting 1: EF = 41 + 13 – 1 = 53.

   

   Figure 6-129.  

3. Answer: B

   To calculate LS for a task that’s the predecssor to two other tasks, start by calculating the LF. Take the lowest LS and subtract 1: LF = 61 – 1 = 61. Then use that LF to calculate LS by subtracting the duration and adding 1: LS = 61 – 13 + 1 = 49.

4. Answer: C

   Don’t let the jargon fool you! You don’t need to know anything about software testing to answer this question. When you have two activities, and the first activity has to be timed so that it finishes before the second one starts, then you’ve got a Finish-to-Start relationship, or FS.

5. Answer: B

   Note

   Did answer A trick you? No need for rolling wave planning when you’ve got enough info to define all the activities!

   This is a which-is-next question that describes a project that’s completed the Define Activities, Sequence Activities, Estimate Activity Resources, and Estimate Activity Durations processes. The next process in Project Schedule Management is Develop Schedule, which means that the next thing you do is create the schedule!

6. Answer: D

   The schedule baseline is an output of the Develop Schedule process, not an input. You should definitely know what goes into the schedule baseline: it’s a specific version of the schedule that you set aside and use for comparison later on, when you want to know if the project is running late.

   

   Figure 6-130.  

7. Answer: A

   You always want to be honest with your estimates. Every project has unknowns and risks, and there’s no way to estimate any activity exactly! Luckily, we have tools to deal with this. You can use reserve analysis, a tool of Estimate Activity Durations, to come up with a contingency reserve that you can use to plan for these risks.

8. Answer: B

   The critical path is the path in the network diagram where any delay will cause a delay in the schedule. These are the activities that cannot slip without making the project late.

9. Answer: A

   When you draw out a network diagram for the activities in the table, you end up with four paths. And you definitely should draw out the activity diagram for a question like this! You’re allowed to use scratch paper on the exam, and this is one place where you should definitely do it. Of the four paths, only one has the longest duration: Start-A-B-C-Finish, which has a duration of 6 + 4 + 8 = 18. That’s the critical path.

10. Answer: C

    Activity F is in the path Start-A-D-E-F-Finish. This path has a duration of 6 + 1 + 1 + 2 = 10. The float of an activity is the longest time it can slip before it affects the critical path. In this case, activity F can slip by 8 without causing the path that it’s on to go beyond the critical path. But any more than that, and its path becomes the new critical path!

    Note

    Did you notice answer A? Don’t forget that the float of any activity in the critical path is zero!

11. Answer: C

    This is the definition of fast-tracking, and you’re probably getting the hang of this one by now. You may get a question like this, but you’ll almost certainly see fast-tracking as an incorrect answer to several questions.

12. Answer: A

    Remember that when you see slack, it’s the same thing as float. Either term could appear on the exam.

13. Answer: B

    This question is asking about the Estimate Activity Durations process. Take a look at the answers—there’s only one answer that’s used in that process: you need to start with the activity list in order to do the estimates for the activities. The other answers are things that are inputs, tools, or techniques for other processes.

    Note

    When a question asks what you’d use for a process, it’s asking you to pick an input, tool, or technique that’s part of the process.

14. Answer: C

    It’s not hard to remember the order in which the Project Schedule Management processes are performed. If you use a little common sense, you can reason your way through a question like this. You need to figure out your planning procedures before you can define your activities, you need to define your activities before you can sequence them, and you need to do all of that before you can build a schedule!

    Note

    Control Schedule isn’t included in the list of processes because if a schedule change happens, you’ll have to go back and revisit the other Project Schedule Management processes. So it doesn’t have a specific order!

15. Answer: A

    You’ll have to know the different kinds of estimating techniques for the exam. You don’t necessarily have to be good at doing them, but you should recognize which are which. Parametric estimating is when you plug values into a formula, program, or spreadsheet and get an estimate. Analogous estimating uses similar activities from past projects to calculate new estimates. Three-point estimating uses an optimistic, pessimistic, and realistic estimate.

16. Answer: C

    This question is asking you to apply the PERT three-point estimation formula: (optimistic time + 4 × most likely time + pessimistic time) ÷ 6. When a question gives you these values directly, it’s easy. But in this case, to answer the question you had to figure out the values for the optimistic time and pessimistic time, which meant that you needed to look at the assumptions that the team was making. The most likely time was given: 27 weeks. The best-case scenario would come in two weeks earlier, at 25 weeks, and the worst case would come in five weeks late, at 32 weeks. So the estimate is (25 weeks + 4 × (27 weeks) + 32 weeks) ÷ 6 = 27.5 weeks.

    Note

    Sometimes you’ll get a question about applying a formula, but you’ll need to read the text in the question to figure out all of the variables.

17. Answer: C

    The path Start-E-D-C-End has a duration of 8 + 2 + 4 = 14, which is the longest total duration in the entire network.

18. Answer: B

    Activity A is on three different paths: Start-A-B-C-End (13), Start-A-D-C-End (12), and Start-A-D-G-End (9). To calculate its float, you take the longest path’s length and subtract it from the length of the critical path: 14 – 13 = 1.

    

    Figure 6-131.  

19. Answer: A

    Note

    Can you think of how a question might quiz you on this information without actually asking you to look at a network diagram?

    Since Activity E is on the critical path, its float is zero, because the float of any activity on the critical path is zero.

20. Answer: A

    The Schedule Management plan tells you how changes to the schedule are to be handled. Any time there’s a change, the first thing you should do is consult the plan to see how it should be handled.

21. Answer: A

    The organizational process assets contain historical information about past projects. When you write up your lessons learned, or create work performance information, you store it in your company’s organizational process asset library! Also, did you notice that answer B was the wrong definition of parametric estimation?

22. Answer: D

    Crashing the schedule is the form of schedule compression that increases cost. This is a difficult question because all of the answers sound good, and one or two are a little misleading! Don’t fall into the trap of choosing an answer because you recognize a valid tool or technique in it. Reserve analysis and three-point estimates are very useful techniques, but they’re not the answer to this question.

23. Answer: C

    This question was really about the definition of duration, and the key to answering it is to understand how duration is different from effort. The correct answer talks about “calendar time,” which is what a duration is: it’s a measurement (or estimate) of how long the activity will take in real life, taking into account the number of people who will be doing the work, the availability of the people and other resources, everyone’s vacation time, time taken away from the schedule because people are pulled off of the activity to work on higher-priority activities, and other real-world factors. That’s different from effort (which is often measured in person-hours), and it’s different from resource estimating (which involves estimating how many people and what other resources will be used for the activity).