An international poll quoted in an Associated Press story (December 14, 2004)

reported low approval ratings for President GeorgeW. Bush among traditional allies of the United States, such as 32% in Canada, 30% in Britain, 19% in Spain, and 17% in Germany. Let Y indicate approval of Bush’s performance

(1 = yes, 0 = no), π = P(Y = 1), c1 = 1 for Canada and 0 otherwise, c2 = 1 for Britain and 0 otherwise, and c3 = 1 for Spain and 0 otherwise.

a. Explain why these results suggest that for the identity link function,

ˆπ

= 0.17

+ 0.15c1 + 0.13c2 + 0.02c3.

b. Show that the prediction equation for the logit link function is logit(πˆ ) =

−1.59 + 0.83c1 + 0.74c2 + 0.14c3.