Interactive statistics

Small simulations for big statistical ideas.

Everything here runs in plain JavaScript. No backend, no database, no special hosting. You can add more tools over time.

Simulation 01

Biased coin simulator

Change the true probability of heads, the number of flips and the speed. The black line shows the observed heads rate after each flip. The red dashed line is the true probability.

Probability of heads 50% Number of flips 400 Animation speed Medium

Flips0

Observed heads—

True probability50%

Difference—

Simulation 02

Bayes diagnostic calculator

Rare events are unintuitive. Adjust prevalence, sensitivity and specificity to see the chance someone really has a condition after a positive test.

Prevalence 5% Sensitivity 95% Specificity 95%

50.0%chance after a positive test

Simulation 03

Sample size and uncertainty

For a simple proportion, larger samples make the uncertainty interval narrower. Try changing the observed rate and sample size.

Observed rate 50% Sample size 100

Estimated interval: —