Table 5.9 Clinical trial relating treatment to response for ve centers. Response Center Treatment Success Failure 1 Active drug 0 5 Placebo D 9 2 Active drug 1 12 Placebo 0 10 3 Active drug 0 7 Placebo 0 S 4 Active drug 6 3 Placebo 2 6 5 Active drug 5 9 Placebo 2 12 Source: Diane Connell. Sandor: Pharmaceuticals Corp. 5.15 Table 5.9 shows results of a randomized clinical trial conducted at ve centers. The purpose was to compare an active drug to placebo for treating fungal infections (1 = success, 0 = failure). For these data. let y = response. :1: = treatment (1 = active. 0 = placebo). and z = center. a. For the model logitEPO' = l) = a + Ba: + g, explain why quasi-complete sep- aration occurs in terms of the effects of center. b. Using a \"no intercept" option so that {5*} refer to the individual centers rather than contrasts with a baseline center, t the model and report 13f and a; and their standard errors. What are the actual ML estimates? c. The counts in the 2 x 2 marginal table relating treatment to response are all pos- itive, so the empty cells do not affect the treatment estimate. Report the esti- mated treatment log odds ratio and show that it does not change when you delete Centers 1 and 3 from the analysis. (When a center has outcomes of only one type, it provides no information about the treatment eect.)