15.6. Table 12.1 in Chapter 12 reported GSS data on political ideology (scaled 1 to 7, with 1 being most liberal) by party affiliation of 1 2 3 4 5 6 7 Democrat 5 18 19 25 7 7 2 Republican 1 3 1 11 10 11 1 Use logistic regression to describe the effect of political ideology on the probability of being a Democrat.

(a) Report the prediction equation, and estimate the probability of Democratic affiliation at ideology level (i)

1 = extremely liberal, (ii) 7 = extremely conservative.

(b) Use the model to test whether the variables are independent.

Report the test statistic, P-value, and interpret.

(c) Use the odds ratio to describe the effect on party affiliation of a change in ideology from(i) 1=extremely liberal to 2 = liberal, (ii) 1 = extremely liberal to 7 = extremely conservative.

(d) Construct and interpret a 95% confidence interval for the population odds ratio in (c), case (i).