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Your statistical Swiss-army knife

🧮 Stats Calculators

Paste your numbers, hit Run, and read a plain-English interpretation — not just a number. Every calculator has a “Load class data” button that drops in real numbers from our dataset so you can see what a real result looks like. These mirror exactly what you'll do in Google Sheets on exam day.

📊 Descriptive Statistics

Units 3–4. Mean, median, mode, range, variance, standard deviation, and quartiles for one list of numbers.

🔔 z-Score & Percentile

Unit 5. How many standard deviations is a score from the mean — and what percentile is it?

🔗 Correlation (Pearson r)

Unit 6. Do two variables move together? Enter two equal-length columns.

📈 Linear Regression

Unit 7. Find the best-fit line (Ŷ = a + bX) and predict Y from any X.

1️⃣ One-Sample t-Test

Unit 10. Is your sample mean different from a known value (μ)? E.g., do students sleep less than 8 hours?

↔️ Independent-Samples t-Test

Unit 11. Compare two separate groups. Demo loads Festinger & Carlsmith's classic $1-vs-$20 dissonance study, hidden in our data.

🔁 Paired-Samples t-Test

Unit 12. Same people measured twice (before vs after). Demo: mood before and after a gratitude exercise.

🎻 One-Way ANOVA

Unit 13. Compare 3+ groups at once. Demo: does animal-compassion differ by diet (omnivore / vegetarian / vegan)?

🪟 Two-Way ANOVA (2×2)

Unit 14 — the grand finale. Two factors at once, plus the interaction. Demo loads a stereotype-threat study: math scores by gender × threat condition. Watch for the interaction.

🧩 Chi-Square: Goodness of Fit

Unit 15 (bonus). Do your observed counts match a claimed distribution? Demo: our class's diet mix vs. the national 90/7/3 split.

🔀 Chi-Square: Test of Independence (2×2)

Unit 15 (bonus). Are two categorical variables related? Demo: gender × diet in our class data — does the meat-is-masculine stereotype survive the counts?

📈 Read-the-Graph Trainer

Unit 14. A line graph appears — you decide whether there's a main effect of the ROW variable (the lines), the COLUMN variable (the x-axis), and an interaction. Cycles through all 8 patterns; hit “Show all 8 patterns” for the complete cheat-sheet.

Sigma says: These calculators are for learning and checking your work — on exams you'll run the same analyses in Google Sheets so you build the muscle memory. Same logic, same numbers, no surprises.