πŸŸͺ 1-Minute Summary

The F-test compares variances between two groups to determine if they’re significantly different. It’s the ratio of two variances: F = variance₁ / varianceβ‚‚. Commonly used to test assumptions before t-tests (equal variance assumption) and as the foundation for ANOVA. F-distribution is right-skewed and always positive.


🟦 Core Notes (Must-Know)

What is an F-test?

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F-statistic Formula

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F-distribution

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When to Use F-test

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Assumptions

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🟨 Interview Triggers (What Interviewers Actually Test)

Common Interview Questions

  1. “Before running a t-test, what should you check about the variances?”

    • [Answer: Check if variances are equal using F-test or Levene’s test]
  2. “What does a large F-statistic indicate?”

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πŸŸ₯ Common Mistakes (Traps to Avoid)

Mistake 1: Forgetting F-test is sensitive to normality

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Mistake 2: Confusing F-test with ANOVA

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🟩 Mini Example (Quick Application)

Scenario

[Comparing variability in two manufacturing processes]

Solution

from scipy import stats

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