10.6 For Table 7.3 from the survey of high school students, let yit = 1 when subject i used substance t (t = 1, cigarettes; t = 2, alcohol; t = 3, marijuana).

Table 10.10 shows output for the logistic-normal model, logit[P(Yit = 1)] =

ui + βt .

a. Interpret { ˆ βt }. Illustrate odds ratio interpretations by comparing use of cigarettes and marijuana.

b. In practical terms, what does the large value for ˆσ imply?

c. In practical terms, what does a large positive value for ui for a particular student represent?