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. The data in Table 11.15 were observed. Figure 11.14 presents the MINITAB output of a two-way ANOVA of the display panel data.
FIGURE 11.14
MINITAB Output of a Two-Way ANOVA of the Display Panel Data

TABLE 11.15
Results of a Two-Factor Display Panel Experiment

a. Interpret the MINITAB interaction plot in Figure 11.14. Then test for interaction with a = .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.

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Tabulated statistics: Panel, Condition os: Panel A 15.5024.50 32.50 13.50 21.50 35 Columns Condition A11 Condition 25 20 15 10 13.50 20.50 29.50 9.50 18.25 22.50 28.50 34.50 17.00 25.63 A1l 17.17 24.50 32.17 13.33 21.79 Cell contents: 4 Time Mean Two-way ANOVA: Time versus Panel, Condition Source Panel Condition Interaction 6 Error Total Panel A Panel B Panel C DF MS 2 218.58 109.292 26.49 0.000 3 1247.46 415.819 100.80 0.000 16.42 2.736 0.66 0.681 49.50 1531.96 4.125 12 23 individiual 95% CIs For Mean Based on Pooled StDev Panel eant- 21.500 18.250 ) 25.625 18.0 21.0 24.0 27.0 Individual 95% CIs For Mean Based on Pooled StDev Condition Mean 17.1667 24.5000 32.1667 13.3333 (--*-*) 12.0 18.0 24.0 30.0 Display Panel Emergency Condition 4 17 14 15 12 21 24 28 37 19 25 24 31 14 34 13 28 31 10 32 15 19 29