The following table gives the average patient waiting time in minutes for patients from a random sample of 16 physicians, classified by type of practice and type of physician

a. Classify each factor as either fixed or random, and justify your classification scheme.
b. Using the accompanying computer output, compute the F statistic corresponding to each of the four possible factor classification schemes.
c. Discuss the analysis of the data when both factors are considered fixed.
d. What are the estimates of the (fixed) effect due to "general practitioner," the (fixed) effect due to "group practice," and the interaction effect (u11 €“ u12 €“ / μ21 €“ μ22), where μij denotes the cell mean in the ith row and jth column of the table of cell means?
e. Interpret the interaction effect observed.
f. What is an appropriate regression model for this two-way ANOVA?
g. How might you modify the model in part (f) to reflect the conclusions made in part (c)?

Type of Practice Physician Type Group Solo General practitioner Specialist 15, 20, 25, 20 30, 25, 30, 35 20, 25, 30, 25 25, 20, 30, 30