Statistics reference & calculators

Distribution tables, statistical tools, and explanations for students and researchers.

Statistical tables

All tables
Z-tableStandard normal probabilitiesz-scoret-tableCritical values for mean tests and intervalsdf, α, tailsChi-square tableCritical values for categorical and variance testsdf, αF-tableCritical values for ANOVA and variance ratiosdf₁, df₂, α

For a central 95% normal interval, the cutoffs are ±1.960. For a t interval, the cutoff depends on degrees of freedom.

Calculators

All 18 calculators

Z-score

Standardize a value

T-test

Compare one mean, two means, or paired data

Pearson correlation

Measure a linear relationship

Standard deviation

Calculate spread and variance

Confidence interval

Estimate a population mean

Sample size

Plan a survey or study

Lessons by subject

All 41 lessons

Descriptive statistics

Summaries, averages, spread, and visualization

5 lessons

Probability

Counting, conditional probability, and distributions

5 lessons

Hypothesis testing

Test statistics, p-values, and interpreting evidence

6 lessons

Regression

Relationships between variables and model assumptions

6 lessons
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