求统计高手解答作业2

1.  Table 9.19 is based on a study with British doctors.
a. For each age, find the sample coronary death rates per 1000 person-years for nonsmokers and smokers. To compare them, take their ratio and describe its dependence on age.
b. Fit a main-effects model for the log rates having four parameters for age and one for smoking. In discussing lack of fit, show that this model assumes a constant ratio of nonsmokers’ to smokers’ coronary death rates over age.
c. From part (a), explain why it is sensible to add a quantitative interaction of age and smoking. For this model, show that the log ratio of coronary death rates changes linearly with age. Assign scores to age, fit the model, and interpret.



2. Table 11.11 is from a Kansas State University survey of 262 pig farmers. For the question ‘‘What are your primary sources of veterinary information?’’ the categories were (A) professional consultant, (B) veterinarian, (C) state or local extension service, (D) magazines, and (E) feed companies and reps. Farmers sampled were asked to select all relevant categories. Table 11.11 shows the (yes, no) counts for each of these five sources cross-classified with the farmers’ education(whether they had at least
some college education) and size of farm (number of pigs marketed annually, in thousands).
QES：
a) Explain why it is not proper to analyze the data by fitting a multinomial model to the counts in the 2*4*5 contingency table cross-classifying education by size of farm by the source of veterinary information, treating source as the response variable.
b) Analyze the association between Education level,size of farm and farm’s primary sources of veterinary information using Weighted Least Square and GEE.

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