A study compared three different display panels for use by air traffic controllers. Each display panel was tested in a simulated emergency condition; 12 highly trained air traffic controllers took part in the study. Four controllers were randomly assigned to each display panel. The time (in seconds) needed to stabilize the emergency condition was recorded. The results of the study are given in Table 11.4. Let μA, μB, and μC represent the mean times to stabilize the emergency condition when using display panels A, B, and C, respectively. Figure 11.4 gives the MINITAB output of a one- way ANOVA of the display panel data. Using the computer output:
a. Test the null hypothesis that μA, μB, and μC are equal by setting α = .05. On the basis of this test, can we conclude that display panels A, B, and C have different effects on the mean time to stabilize the emergency condition?
b. Consider the pairwise differences μB – μA, μC – μA, and μC – mB. Find a point estimate of and a Tukey simultaneous 95 percent confidence interval for each pairwise difference. Interpret the results by describing the effects of changing from using each display panel to using each of the other panels. Which display panel minimizes the time required to stabilize the emergency condition?