Question

To test whether students in a higher grade level will be less disruptive in class, a school psychologist records the number of documented interruptions during one day of classes from nine local high schools. The sample consisted of nine

(n = 9)

freshman, sophomore, junior, and senior high school classes. The data for each high school class are given in the table.

High School Class
Freshman	Sophomore	Junior	Senior
4	0	5	3
5	1	4	5
3	4	3	2
4	2	5	2
1	1	0	4
2	4	6	4
2	4	3	3
0	0	4	5
1	5	0	2

(a) Complete the F-table. (Round your answers to two decimal places.)

Source of Variation	SS	df	MS	F
Between groups
Within groups (error)
Total

(b) Is it necessary to compute a post hoc test? Explain. (Assume alpha equal to 0.05.)

Yes, post hoc analyses are appropriate because the ANOVA is significant.No, post hoc analyses are not appropriate because the ANOVA is not significant.    

Answer 1

a) The F table will be :

Source of Variation	SS	df	MS	F
Between Groups	8.083	3	2.694	0.86
Within Groups(Error)	100.222	32	3.132
Total	108.306	35

b) Since P-value for F test = 0.472 > 005, so we fail to reject H₀ at 5% level of significance and we can conclude that there are no significant difference between means due to different classes.

ans-> No, post hoc analyses are not appropriate because the ANOVA is not significant.