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Advanced Proof

CI for Ratio of Variances: Relative Spread

Students frequently invert the F-critical values, confusing the degrees of freedom ordering (n1−1,n2−1) (n_1-1, n_2-1) versus (n2−1,n1−1) (n_2-1, n_1-1) . Always remember: the numerator degrees of freedom of the statistic must match the sample size of the numerator variance.
Institutional Reference: Statistical Inference I
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