Ten randomly selected mental institutions were examined to determine the effects of three different antipsychotic drugs on patients with the same types of symptoms. Each institution used one and only one of the three drugs exclusively for a one-year period. The proportion of treated patients in each institution who were discharged after one year of treatment is as follows for each drug used:
Drug 1: 0.10, 0.12, 0.08, 0.14 (1. = 0.11, S1 = 0.0192)
Drug 2: 0.12, 0.14, 0.19 (2. = 0.15, S2 = 0.0361)
Drug 3: 0.20, 0.25, 0.15 (3. = 0.20, S3 = 0.0500)
a. Determine the appropriate ANOVA table for this data set using the accompanying computer output.
b. Test to see whether significant differences exist among drugs with regard to the average proportion of patients discharged.
c. What other factors should be considered in comparing the effects of the three drugs?
d. What basic ANOVA assumptions might be violated here?