10.17 Refer to the insomnia example in Section 10.3.1.

a. From results in Table 10.7 for the GLMM, explain how to get the interpretation quoted in the text that “The response distributions are similar initially for the two treatment groups, but the interaction suggests that at the follow-up response the active treatment group tends to fall asleep more quickly.”

b. According to SAS, the maximized log likelihood equals −593.0, compared with−621.0 for the simpler model forcing σ = 0. Compare models, using a likelihood-ratio test. What do you conclude?