Statistics calculators

Calculate sample and population standard deviation, variance, mean, and spread interpretation.

Estimate confidence interval from mean, standard deviation, sample size, and confidence level.

Estimate sample size from confidence level, margin of error, population, and expected proportion.

Calculate z-score, standard deviations from mean, and normal-distribution context.

Plan how to allocate a fixed sample across study groups using effect size, cost, and dropout assumptions.

Estimate the sample size and detectable effect needed for a replication study under conservative assumptions.

Estimate false-positive pressure from multiple tests, optional stopping, and subgroup exploration.

Estimate familywise error pressure from parallel hypotheses and planned correction strategy.

Estimate sample size needed to reach a target confidence interval width for a measured outcome.

Translate between standardized effect size, raw-unit difference, pooled spread, and practical interpretation.

Estimate potential bias from response rate, population difference, and missing-response assumptions.

Estimate how sample size, confidence level, and response variability consume a margin-of-error budget.

Estimate citation half-life and literature freshness from publication year, citation age, and field velocity.