Start From
Your Research Question
Find the question you're asking and pick from the methods that answer it. Then check each one's “This Is Not Your Test If…” before you commit.
Compare Groups or Conditions
Compare a Group to a Known Value
Does a group's average score, typical score or share of yes answers differ from a guideline, norm or published figure?
Narrow These Down →Compare Two Groups
Do two independent groups differ on average, or does one tend to score higher?
Narrow These Down →Compare Two Conditions in the Same People
Do the same people score differently in two conditions or at two times?
Narrow These Down →Compare Three or More Groups
Do several groups or conditions differ on average, or do some tend to score higher?
Narrow These Down →Test Whether One Effect Depends on Another
Does the effect of one factor change with the level of another (an interaction)?
Narrow These Down →Compare Proportions or Categories
Do groups or conditions differ in how often each category or outcome turns up?
Narrow These Down →Look at a Relationship
Explain How an Effect Happens
Does one variable relate to another through a third, intervening variable?
Narrow These Down →Test Whether a Relationship Depends on a Third Variable
Is the link between two variables stronger, weaker or reversed for people who score higher on a third (a moderator)?
Predict an Outcome
Account for Clustered Data
How do predictors at each level relate to an outcome when people come in groups, such as students in classrooms or patients in clinics?
Narrow These Down →Predict a Yes/No or Category Outcome
Which variables predict whether something happens, or which category someone ends up in, and how much does each change the odds?
Narrow These Down →Check a Measure's Quality
Check That a Measure Is Reliable
Does a measure give consistent scores across occasions, raters or items?
Narrow These Down →Check That a Measure Measures What It Should
Do a measure's scores reflect the construct it's meant to capture, and not other constructs?
Narrow These Down →Test a Structure Named in Advance
Do a set of measures reflect the underlying traits a theory says they should, in the pattern it predicts?
Evaluate the Items on a Test
How well does each item on a test or scale work, and which ones need revising or dropping?
Narrow These Down →Find the Structure behind a Set of Items
How many underlying dimensions do a set of items reflect, and which items go together?
Evaluate a Screening or Diagnostic Test
How well does a test, questionnaire or cutoff pick out the people who have a condition, judged against a reference standard?
Narrow These Down →Describe or Explore Data
Describe Your Data
What's a typical score, how spread out are the scores, and what shape do they take?
Check a Distribution's Shape
Do the scores follow a named distribution, such as the normal curve?
Find Groups of Similar People
Do people fall into groups, or profiles, on a set of measures, and what does each group look like?
Model Change over Time
Model Change over Time
How does an outcome change across repeated measurements of the same people, and do people differ in how they change?
Narrow These Down →Model How People Move between States
How likely are people to move from one category to another from one occasion to the next, and where do they tend to end up?