Choosing a statistical test
Which Statistical Test Should I Use? A Simple Decision Guide
Answer three questions about your goal, your variables and your design, and this guide points you to the right test, with a free tool to run it.
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research methods
Sample size and power
How to Calculate Sample Size: Surveys, Experiments and Power Analysis
Work out how many participants you need, whether you are estimating a percentage in a survey or testing a hypothesis, with formulas, quick-reference tables and free calculators.
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Independent Samples T-Test CalculatorFree two-sample t-test calculator with Student and Welch results, Levene’s test, 95% CI, Cohen’s d and Hedges’ g. Paste data from Excel.One-Way ANOVA CalculatorFree one-way ANOVA calculator with Levene’s test, Welch’s F, eta squared, omega squared and Tukey HSD post-hoc comparisons. APA tables in seconds.Chi-Square Test of Independence CalculatorFree chi-square test calculator from raw data or a contingency table: expected counts, Yates correction, likelihood ratio, Cramér’s V and residuals.Multiple Linear Regression CalculatorFree multiple regression calculator: B, SE, standardized beta, t, p, 95% CI and VIF for each predictor, with R², ANOVA and automatic dummy coding.Cronbach’s Alpha CalculatorFree Cronbach’s alpha calculator: reliability with 95% CI, standardized alpha, corrected item-total correlations and alpha if item deleted.PROCESS Macro OnlineRun Hayes’ PROCESS macro models 1 to 76 online, free: mediation, moderation, moderated mediation, bootstrap CIs and index of moderated mediation.CB-SEM Studio app (drag-and-drop model builder)Free CB-SEM app: draw your SEM model, run CFA and SEM by maximum likelihood, and get fit indices, CR, AVE, HTMT, mediation and modification indices.PLS-SEM Studio appFree PLS-SEM app: draw your model, run bootstrapping, test mediation and moderation, check HTMT and reliability, and run fsQCA. Nothing to install.Exploratory Factor Analysis (EFA) OnlineFree exploratory factor analysis online: KMO, Bartlett’s test, principal axis factoring, varimax rotation, scree plot and sorted factor loadings.Mann-Whitney U Test CalculatorFree Mann-Whitney U test (Wilcoxon rank-sum) calculator with mean ranks, z, exact or asymptotic p-value and effect size r. For ordinal or skewed data.Power Analysis and Sample Size CalculatorFree a priori power analysis for t-tests, ANOVA, correlation, proportions, chi-square and regression. Required sample size and power curve, like G*Power.Data Cleaning and Coding ToolClean and code data online for free: SPSS-style variable view, value labels, recode, reverse-code Likert items, missing values, duplicates and outliers.