Job satisfaction of truck drivers. Turnover among truck drivers is a major problem for both carriers and shippers. Since knowledge of driver-related job attitudes is valuable for predicting and controlling future turnover, a study of the work-related attitudes of truck drivers was conducted (Transportation Journal, Fall 1993).

The two factors considered in the study were career stage and time spent on road. Career stage was set at three levels: early (less than 2 years), mid-career (between 3 and 10 years), and late (more than 10 years). Road time was dichotomized as short (gone for one weekend or less) and long (gone for longer than one weekend). Data were collected on job satisfaction for drivers sampled in each of the 3 × 2 = 6 combinations of career stage and road time. [Job satisfaction was measured on a 5-point scale, where 1 = really dislike and 5 = really like.

(a) Identify the response variable for this experiment.

(b) Identify the factors for this experiment.

(c) Identify the treatments for this experiment.

(d) The ANOVA table for the analysis is shown here. Fully interpret the results.

(e) The researchers theorized that the impact of road time on job satisfaction may be different depending on the career stage of the driver. Do the results support this theory?

(f) The researchers also theorized that career stage affects the job satisfaction of truck drivers. Do the results support this theory? ∗

(g) Since career stage was found to be the only significant factor in the 3 × 2 factorial ANOVA, the mean job satisfaction levels of the three career stages (early, middle, and late) were compared using the Bonferroni method. Find the adjusted α level to use in the analysis, if the researchers desire an overall significance level of α = .09. ∗

(h) The sample mean job satisfaction levels for the three career stages are given here. Assuming equal sample sizes for each stage and a Bonferroni critical difference of B = .06, rank the means.