Question

You must include all EXCEL printouts and the 6 step write-up for both problems. The questions are given below.

USING ANOVA: Assuming variances are equal.

Concerned about Friday absences, management examined the number of persons absent for each of the past three Fridays. Does this sample provide sufficient evidence to conclude there is a significant difference in the average number of absences? Use alpha = .05.

Plant 1	Plant 2	Plant 3	Plant 4
19	17	27	22
24	20	32	27
20	16	27	25

1. Is there sufficient evidence of a difference in the variances in number of absences among the four plants? (Set alpha = to .05)

2. Provide the p-value for part a, and explain its meaning in words.

3. Is there sufficient evidence to indicate a difference in the mean number of absences among the four plants? (Set alpha = to .05)

4. Provide the p-value for part a, and explain its meaning in words.

5. If there is a difference in the means, what test would you use to figure out which ones are different?

Answer 1

Using Minitab software, (Stat -> ANOVA -> Test for equal variances), we get

b) Since p-value = 0.956 > 0.05, so we fail to reject H₀ and we can conclude that there is no sufficient evidence of a difference in the variances in number of absences among the four plants.

c) Using Minitab software, (Stat -> ANOVA -> One way), we get

Since P-value = 0.004 < 0.05, so at 5% level of significance, we reject H₀ and we can conclude that there is significant difference in the mean number of absences among the four plants.

e) Since there is a difference in the means,  to figure out which ones are different, one need to use independent samples t test.