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Chi-squared tests
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Learn it For a contingency table, expected count = (row total × column total) ÷ grand total. χ² = Σ(observed − expected)²/expected, and degrees of freedom = (rows − 1)(columns − 1). A large χ² (small p-value) means the variables are probably not independent.
Example: Row total 40, column total 30, grand total 120. Expected count?
- 40 × 30 ÷ 120.
- = 10.
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