Y = whether a patient having surgery withgeneral anesthesia experienced a sore throat on waking (1 = yes) as a function of D = duration of the surgery (in minutes) and T = type of device used to secure the airway (0 = laryngeal mask airway, 1 = tracheal tube).
a. Fit a main effects model using these predictors. What is the predicted probability function? Interpret the signs of the parameter estimates.
b. What is the odds ratio for sore throat when the surgery time increases by 10 minutes, adjusting for the device used? Does surgery time has a significant effect on the probability of developing a sore throat?
c. Fit a model permitting interaction. Report the effect of increasing surgery time by 10 minutes on developing a sore throat when (i) T = 0, (ii) T = 1.
d. Conduct a likelihood ratio test about whether you need the interaction term in (c).