For Psychology Students
Choose the right statistical test - read the key SPSS output - know what your p-value means
1. Which statistical test should I use?
Your research question / data Common test What it answers
Relationship between two continuous variables Pearson correlation Are the variables linearly related?
Relationship with ordinal / non-normal data Spearman correlation Is there a monotonic association?
Compare 2 independent groups Independent-samples t-test Do the two group means differ?
Compare the same participants twice Paired-samples t-test Did scores change across two related measurements?
Compare 3+ independent groups One-way ANOVA Does at least one group mean differ?
Association between categorical variables Chi-square test Are the categorical variables associated?
Predict a continuous outcome Linear regression How well do predictor(s) explain/predict the outcome?
Quick warning: test choice also depends on study design, measurement level, assumptions, independence and the exact
research question. Use this as a decision aid, not as a substitute for checking assumptions.