Power Analysis and Sample Size Calculators
Plan a study before collecting data: how many participants you need for enough power, how many survey responses give a target margin of error, and whether an A/B test result is real.
Power Analysis and Sample Size Calculator
Sample size for t-tests, ANOVA, correlation, proportions, chi-square and regression, like G*Power.
Replaces G*Power · PASSSurvey Sample Size Calculator
How many respondents a survey needs for a given margin of error and confidence level.
A/B Test Significance Calculator
Compare conversion rates of two variants with a two-proportion z-test, uplift and confidence interval.
Power Analysis and Sample Size Calculator
Run it before collecting data to justify your sample size, as most ethics boards and grant reviewers require.
Survey Sample Size Calculator
Use it for descriptive surveys that estimate a percentage. For comparing groups or testing hypotheses, use the power analysis tool.
A/B Test Significance Calculator
Use it to evaluate landing pages, emails or app features where the outcome is a conversion (yes/no). Decide the sample size before starting, using the power analysis tool with two proportions.
Other categories
Data cleaning and preparation · Describe and explore · Compare means · Nonparametric tests · Correlation and regression · Bayesian statistics · Categorical data · Reliability and agreement · Multivariate analysis · Structural equation modeling · Econometrics and time series · Panel data and causal inference · Marketing and decision research · Survival, clinical and meta-analysis · PLS-SEM