A study compared three display panels used by air traffic controllers. Each display panel was tested for four different simulated emergency conditions. Twenty- four highly trained air traffic controllers were used in the study. Two controllers were randomly assigned to each display panel– emergency condition combination. The time ( in seconds) required to stabilize the emergency condition was recorded. Figure 11.12 gives the resulting data and the MINITAB output of a two-way ANOVA of the data. Using the computer output:
a. Interpret the interaction plot in Figure 11.12. Then test for interaction with α = .05.
b. Test the significance of display panel effects with α = .05.
c. Test the significance of emergency condition effects with α = .05.
d. Make pairwise comparisons of display panels A, B, and C by using Tukey simultaneous 95 percent confidence intervals.
e. Make pairwise comparisons of emergency conditions 1, 2, 3, and 4 by using Tukey simultaneous 95 percent confidence intervals.
f. Which display panel minimizes the time required to stabilize an emergency condition? Does your answer depend on the emergency condition? Why?
g. Calculate a 95 percent (individual) confidence interval for the mean time required to stabilize emergency condition 4 using display panel B.