Statistics for Data Analysis by Hand

Preview

What it teaches

The statistics behind everyday reports and dashboards: mean, median and mode (and why one big value drags the mean), range, variance and standard deviation (sample vs population), z-scores, the 68-95-99.7 rule, quartiles, IQR and outlier fences, correlation and a least-squares line, why correlation isn’t cause, and a 95% confidence interval for a mean. All by hand on small data. The AI asks 3 questions, places you, shows a short card per module, then gives you one problem at a time and checks your answer against keys computed by script, and when your wrong answer is one of the common slips listed for that problem it names it (“that divides by n; a sample divides by n − 1”); otherwise it shows the key and the working.

Analysts, students and career-changers who use averages, dashboards and A/B tests but never learned what the numbers mean. It teaches describing data and reading an estimate. It does not teach hypothesis tests, so it will not tell you whether an A/B result is significant.

How long

40 items. About 45-60 rounds for a beginner (a simulated run took 56; for someone who already knows the basics it took 15) plus a 12-item final: 2-3 sessions (not timed with a real student). The tutor gives a one-line save code at the end of each session.