StatQuest with Josh Starmer on YouTube · Open on YouTube
Core skills: SQL depth, statistics, Python and dashboards · Advanced beginner · Lesson 19 of 99 · 8 min video, then about 4 hours of practice
Sampling, the central limit theorem and confidence intervals
After this you can explain why sample averages vary, construct and interpret a confidence interval, and say what a margin of error does and does not mean.
Why it matters
Every number an analyst reports is an estimate with uncertainty. Learn the central limit theorem intuitively (averages of samples are approximately normal even when the data is not) and what a 95 percent confidence interval actually claims. The trap is saying 'there is a 95 percent chance the true value is in this interval'; the correct reading is about the method, and getting it right matters when someone asks how sure you are.
How to use this resource
StatQuest's intuitive explanation of the central limit theorem. Watch it before the confidence-interval video.