Interactive statistics · built for STAT 251 and beyond
Don't memorize statistics — see them.
Five short, hands-on chapters. Draw samples, watch the Central Limit Theorem appear out of any population, catch 95% confidence intervals miss, drag your own data into hypothesis tests, and fit regression lines by feel. Everything runs right here in your browser — no installs, no network.
First time here? Pick a chapter below (or swipe with the arrows), read
one short paragraph, then touch the figures — every dot, slider and button does
something. Nothing in this app is real data except the Moscow, Idaho temperatures in Chapter 1.
Chapter 1 / 5
Sampling
Data & sources
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Real data — daily maximum air temperature, MOSCOW U OF I, Moscow, Idaho
(2015-01-01 → 2025-12-31, 4,018 days).
NOAA National Weather Service Cooperative Observer Program (COOP station
USC00106152, campus, elevation 2634 ft), served by the NOAA Regional Climate Centers' Applied Climate Information System (RCC-ACIS), rcc-acis.org, endpointdata.rcc-acis.org/StnData, retrieved 2026-09-13. Raw response stored unmodified indata/raw/acis_moscow_maxt_2015-2025.json; the app embeds the parsed values. US government data; ACIS terms: data provided as-is, recent values preliminary. - Everything else is simulation. All samples, populations, intervals, test statistics and scatter plots in Chapters 2–5 (and the N(0, 1) sample of 30 in Chapter 1) are randomly generated in your browser on each page load or when you press a button. They are illustrative, not real measurements — numbers differ every time on purpose, so you can see the variability you're studying.
University of Idaho · STAT 251 explorable explanations · Built with Codex on MindRouter. Single self-contained file, no network requests.