solution

Performance of a bus depot. Refer to the International Journal of Engineering Science and Technology (February 2011) study of public bus depot performance, Exercise 9.25 (p. 544). Recall that 150 customers provided overall performance ratings at each of three different bus depots (Depot 1, Depot 2, and Depot 3). The average performance scores were determined to be significantly different at  = .05 using an ANOVA F-test. The sample mean performance scores were reported as ₁ = 67.17, x2 = 58.95, and ³ = 44.49. The researchers employed the Bonferroni method to rank the three performance means using an experimentwise error rate of .05. Adjusted 95% confidence intervals for the differences between each pair of treatment means are shown in the table. Use this information to rank the mean performance scores at the three bus depots.

Exercise 9.25

Performance of a bus depot. The performances of public bus depots in India were evaluated and ranked in the International Journal of Engineering Science and Technology (February 2011). A survey was administered to 150 customers selected randomly and independently at each of three different bus depots (Depot 1, Depot 2, and Depot 3); thus, the total sample consisted of 450 bus customers. Based on responses to 16 different items (e.g., bus punctuality, seat comfort, luggage service, etc.), a performance score (out of 100 total points) was calculated for each customer. The average performance scores were compared across the three bus depots using an analysis of variance. The ANOVA F-test resulted in a p-value of .0001.

a. Give details (experimental units, dependent variable, factor, treatments) on the experimental design utilized in this study.

b. The researchers concluded that the “mean customer performance scores differed across the three bus depots at a 95% confidence level.” Do you agree?