Question

 

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 resulting data and analysis results are given below.

Display panel data
	Emergency condition
Display panel	1	2	3	4
A	17	25	31	14
	14	24	34	13
B	15	22	28	9
	12	19	31	10
C	21	29	32	15
	24	28	37	19

Two-way ANOVA results
Source of Variation	DF	SS	MS	F	P
Panel	2	218.58	109.29	26.49	0.000
Condition	3	1247.46	15.82	100.80	0.000
Interaction	6	16.42	2.74	0.66	0.681
Error	12	49.50	4.13
Total	23	1531.96

Tasks:

• Set up null and alternative hypotheses to (a) test the significance of display panel effect, (b) test the significance of emergency condition effects, and (c) test the interaction a between the two factors.
• Justify the type of ANOVA (one-way or two-way) you will apply to test the hypotheses.
• Interpret the p values in the results table for an accept/reject decision regarding the hypotheses.
• State your conclusions including what the ANOVA results do not tell you and your needed actions as a researcher.

Answer 1

Froom the given ANOVA table, the p-value for a term tells you whether the effect for that term is significant:.

• If P is less than or equal to the a-level you have selected, then the effect for the term is significant.
• If P is larger than the a-level you have selected, the effect is not significant.

a

The p-value for the Panel factor is given as 0.000. This means that the actual p-value is less than 0.0005. Since this is less than the chosen a-level of 0.05, it means the effect of panel on air traffic controllers is significant.

·b.The p-value for condition is also less than 0.05, indicating that there is also a significant effect of condition on air traffic controllers .

c.. The p-value for the interaction term (0.681) is greater than 0.05. Thus, the interaction of the panel and condition factors is not significant, and you are free to consider the effects of the individual factors separately.

d. Two way ANOVA