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Unformatted text preview: Stat 665 (Spring 2011) Kaizar Homework 7 Due at the beginning of class, Friday May 27 . Aim of Homework : To interpret models to fit multivariate outcomes. To fit and interpret log- linear models. Reading : An Introduction to Categorical Data Analysis, 2nd edition: Chapter 6.1-6.2, Chapter 7.1-7.3 Exercises : 40 points total. 1. Nominal Regression (12 points) Table 6.17 on page 199 of Agresti results from a clinical trial for the treatment of small-cell lung cancer. Patients were randomly assigned to two treatment groups. The sequential therapy administered the same combination of chemotherapeutic agents in each treatment cycle. The alternating therapy used three different combinations, alternating from cycle to cycle. I fit two multinomial baseline-category logit model predicting the category of response. The first is an intercept-only model. The second has the therapy as an explanatory variable. Partial results from R are reported here: Call: vglm(formula = cbind(PD, NC, PR, CR) ~ 1, family = multinomial, data = cancerdf) Residual Deviance: 16.47901 on 9 degrees of freedom Call: vglm(formula = cbind(PD, NC, PR, CR) ~ Treat, family = multinomial, data = cancerdf) Coefficients: Value Std. Error t value (Intercept):1 0.13353 0.258770....
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- Spring '10