Problems 13.1. in a clinical trial of patients with respiratory illness, 111 patients from two different clinics were randomized to receive either placebo or an active treatment. Patients were examined at baseline and at four visits during treatment. At each examination, respiratory status was detemrined. These data are from Kock et al. (1990), and are reported in Davis (1991) and Stokes et al., (1995). The main objective of the analyses is to understand the joint effects of treatment and time on the probability that respiratory status is classified as good. It is also of interest to determine wheter the effect of treatment is the same for patients from the two clinics. The raw data are stored in an external file: respir.dat. Each row of the data set contains the following eight variables" ID CLinic Treatment Yo y1 y2 y3 y4. Problems 13.1.1 to 13.3.8 - SAS codes and interpretations