Statistics calculators

Sample size, correlations, t and chi-square tests, reliability and effect size.

Tools in this category

How many responses you need for your survey to be representative.

Sample and population deviation, variance and coefficient of variation.

How precise your survey is, given the sample you actually collected.

How many standard deviations a value sits from the mean and which percentile it occupies.

Aimed at research projects, theses and instrument validation. Each test reports its statistic, the degrees of freedom and the associated p-value.

p-values are computed from the exact distributions (Student's t and chi-square), not from approximate lookup tables.