Table 9.5 refers to a clinical trial comparing a new drug (d = 1) with a standard drug (d = 0) for subjects suffering mental depression. Initial severity of depression was recorded as mild (s = 0) or severe (s = 1). In each group, subjects were randomly assigned to one of the two drugs. Following t = I week, 2 weeks, and 4 weeks of treatment, each subject's level of mental depression was classified as normal ( y, = 1) or abnormal (1, = 0). a. With scores (0, 1, 2) for t and exchangeable working correlation and permitting a d x t interaction, we obtain the GEE results shown next. Find and interpret the estimated time effect for each drug. Estimate Naive S.K. Naive z Robust S.E. Robust z ( Intercept) -0. 02810 0.16255 -0.17286 0 .17418 -0.16132 severity TGETE I- 0 . 14486 -9. 07004 0 .14596 -9.00167 drug -0. 05927 0 . 22053 -0.26874 0 .22856 -0.25931 time 0. 48246 0 . 11412 4.22786 0 .11994 4. 02260 drug:time 1. 01719 0.18771 5.41910 0.18770 5. 41921 Explain why at he The with the news