Professor I M Smart was concerned ...

MSmartwasconcernedabouttheextenttowhich.xls

Sheet1


A	B	C	D
70	60	60	100
50	60	80	90
70	70	80	70
60	50	90	80
40	50	70	60
60	70	100	80
40	40	70	70
50	80	80	90
90	70	100	70
60	90	50	80
						Ho: All groups have the same mean grade
One factor ANOVA						Ha: At least two groups differ significantly in their mean grade
(1)	Mean	n	Std. Dev			(2) F = 4.66; Df (N) = 3, Df (D) = 36
70.0	59.0	10	15.24	A
70.0	64.0	10	15.06	B		(3) p- value = 0.0075
70.0	78.0	10	16.19	C
70.0	79.0	10	11.97	D		(4) Since 0.0075 < 0.05, we reject Ho. The studying habits appear the affect the final grades significantly.
	70.0	40	16.64	Total
						(5) Yes, the average grade is highest for group D. So a student's chance of obtaining a good grade is higher if he/she often shows up during office hours.
ANOVA table
Source	SS	df	MS	F	p-value
Treatment	3,020.00	3	1,006.667	4.66	.0075
Error	7,780.00	36	216.111
Total	10,800.00	39


One factor ANOVA
	Mean	n	Std. Dev
70.0	59.0	10	15.24	A
70.0	64.0	10	15.06	B
70.0	78.0	10	16.19	C
70.0	79.0	10	11.97	D
	70.0	40	16.64	Total
ANOVA table
Source	SS	df	MS	F	p-value
Treatment	3,020.00	3	1,006.667	4.66	.0075
Error	7,780.00	36	216.111
Total	10,800.00	39
Post hoc analysis
p-values for pairwise t-tests
		A	B	C	D
		59.0	64.0	78.0	79.0
A	59.0
B	64.0	.4519
C	78.0	.0065	.0401
D	79.0	.0044	.0285	.8800
Tukey simultaneous comparison t-values (d.f. = 36)
		A	B	C	D
		59.0	64.0	78.0	79.0
A	59.0
B	64.0	0.76
C	78.0	2.89	2.13
D	79.0	3.04	2.28	0.15
critical values for experimentwise error rate:
		0.05	2.70
		0.01	3.35

Comparison of Groups