Isotoon explains statistics by showing what a number lets you say. Ask about p-values, confidence intervals, sampling or regression and get a short animated video that runs the samples, so you can watch the idea play out.
Statistics is mostly about what a number lets you say and what it does not. Ask about the idea you keep second-guessing and see it play out with samples you can watch.
A p-value is the probability of getting results at least as extreme as yours if the null hypothesis were true. A small p-value says your data would be surprising under the null hypothesis, which counts as evidence against it. It is not the probability that the null hypothesis is true, and it says nothing about how large or important an effect is.
Take many random samples of the same size from a population and compute each sample's mean. As the sample size grows, the distribution of those means gets closer to a normal curve centered on the population mean, with a spread equal to the population's standard deviation divided by √n. That holds for almost any population shape, which is why normal-based intervals and tests work even when the data themselves are not normal.
A 95% confidence interval comes from a method that captures the true value in 95% of samples. If you repeated the study many times and built an interval each time, about 95 out of 100 of those intervals would contain the true value. Any one interval either contains it or does not; the 95% describes the method, not a single interval.
The ones marked 3D become a model you can turn, step through and tap.
Every claim is checked before anything is drawn, and every video lists its sources. See plans