Refer to Table 11.4.

Fit the interaction model

logit[P(Y₂ ‰¤ j)] = α_j + β₁x + β₂ y₁ + β₃ xy₁

that constrains effects {β₁x + β₂ y₁ + β₃ xy₁} to follow the pattern (Ï„, Ï„, λ + σ, λ) for the active group and (Ï„, Ï„, σ, 0) for the placebo group. Interpret λ̂.

Table 11.4:

Time to Falling Asleep, by Treatment and Occasion Time to Falling Asleep Follow-up < 20 > 60 Treatment Initial 20-30 30-60 < 20 Active 4 20-30 5 2 11 30-60 13 23 > 60 < 20 17 13 Placebo 4 20-30 14 30-60 6. 18 > 60 4 11 14 22