A sample of 45 auditors was randomly divided into three groups: (l) the 15 auditors in group 1 designed an audit program for accounts receivable and evaluated an audit program for accounts payable designed by somebody else; (2) the 15 auditors in group 2 did the reverse; (3) the 15 auditors in group 3 (the control group) evaluated the audit programs for both accounts. All 45 auditors were then instructed to spend an additional 15 hours investigating suspected irregularities in either or both of the audit programs. The mean additional number of hours allocated to the accounts receivable audit program by the auditors in groups 1,2, and 3 were 1 = 6.7, 2 = 9.7, and 3 = 7.6. Furthermore, a one-way ANOVA of the data shows that SST = 71.51 and SSE = 321.3.
a. Define appropriate treatment means µ1, µ2, and µ3. Then test for statistically significant differences between these treatment means. Set α = .05. Can we conclude that the different auditor groups have different effects on the mean additional time allocated to investigating the accounts receivable audit program?
b. Perform pairwise comparisons of the treatment means by computing a Tukey simultaneous 95 percent confidence interval for each of the pairwise differences µ1 - µ2, µ1 - µ3 and µ2 - µ3. Interpret the results. What do your results imply about the objectivity of auditors? What are the practical implications of this result?