Calculators
Run a test on numbers you already have. Each one names the paper its formula comes from, and links to the page explaining when it is the wrong tool.
Before you collect data
§0.1Sample size & powerDescribe your data
§1.1Descriptive summaryCompare two groups
§2.1Chi-square (2×2, Yates)§2.2Fisher's exact (2×2)§2.3Independent t-test (Welch)§2.4Mann–Whitney U§2.5Paired t-test§2.6Wilcoxon signed-rank§2.7Pearson correlation§2.8Spearman correlation§2.9Treatment 2×2 — RR, OR, NNTAdjust for confounding
§4.1Multivariable analysis — guidedTime-to-event
§5.1Kaplan–Meier & log-rankEvaluate a test
§6.1Diagnostic 2×2 — Sens, Spec, Youden