Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works
🔲

Chi-Square Degrees-of-Freedom Sprint

Independence's (r-1)(c-1), or goodness-of-fit's k-1 -- the same n-1 mistake tempts both, and this sprint drills telling them apart.

⏱️ 60s
▶ Log in to play

← Back to the arcade