Lesson 17 of 20 · about 16 min

Confidence intervals

A poll says "52% support, plus or minus 3 points, with 95% confidence." What does that really promise? You'll draw hundreds of intervals from a machine whose true average you secretly know, count how many catch it, and learn exactly what "95% confident" means, what makes an interval wider or narrower, and what it can't protect you from.