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Introduction to Categorical Data Analysis

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364 BRIEF SOLUTIONS TO SOME ODD-NUMBERED PROBLEMS<br />

b. LR statistic = 32.9(df = 2), P0 when LI < 0.9625/0.032 = 30.1. So, ˆπ increases as LI increases<br />

up <strong>to</strong> about 30.<br />

d. Simpler model with linear effect on logit seems adequate.<br />

11. Model seems adequate. A reference for this type of approach is the article by<br />

A. Tsiatis (Biometrika, 67: 250–251, 1980).<br />

15. Logit model with additive fac<strong>to</strong>r effects has G 2 = 0.1 and X 2 = 0.1, df = 2.<br />

Estimated odds of females still being missing are exp(0.38) = 1.46 times those<br />

for males, given age. Estimated odds considerably higher for those aged at least<br />

19 than for other age groups, given gender.<br />

17. a. For death penalty response with main effect for predic<strong>to</strong>rs, G 2 = 0.38, df = 1,<br />

P = 0.54. Model fits adequately.<br />

b. Each standardized residual is 0.44 in absolute value, showing no lack of fit.<br />

c. Estimated conditional odds ratio = exp(−0.868) = 0.42 for defendant’s race<br />

and exp(2.404) = 11.1 for victims’ race.

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