• Association – when one thing is shown to be linked to another, but is not necessarily the cause. This is not the same as causation.
• Biases – factors in studies that may make the results skewed in one way or another. To avoid biases, researchers will try to make them randomized, blinded and placebo-controlled.
• Blinded trial – a study in which subjects and/or researchers do not know which treatment subjects are getting until after the trial is complete.
• Case-controlled trial – a study that uses matching to compare people with and without certain conditions or characteristics to see if they have an association.
• Causation – when one thing has absolutely, positively been proven to be the reason that something else happens. Can only be done with a randomized controlled trial.
• Clinical significance – a subset of results with statistical significance that also have meaning in real life.
• Cochrane Collaboration – a public warehouse of high-quality systematic reviews and meta-analyses.
• Cohort study – a study that usually follows large groups of people over time to see what happens to them, without interfering in their care.
• Matching – in a case-controlled trial, different types of people are paired with each other based on pre-selected characteristics, like age or sex.
• Meta-analysis – a special type of systematic review that uses statistics to combine the results of all the included studies.
• Placebo-controlled – well-designed studies have one group getting a ‘fake’ or placebo treatment in order to hide which people are getting the intervention and which are getting nothing.
• Randomized – in the best kind of studies, people are chosen at random as to how they are treated. Such studies are called randomized trials.
• Randomized controlled trial – a study that is randomized and placebo-controlled. These studies are the only type that can prove causation.
• Statistical significance – a mathematical calculation showing an association or causation to be very probably true. Differs from clinical significance in that the significance may not be meaningful in real life.
• Systematic review – A formalized compilation, using a documented scientific method, of all the relevant studies on a particular topic.