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st: Anova with repeated variable


From   VIVIAND Xavier <Xavier.Viviand@mail.ap-hm.fr>
To   statalist@hsphsun2.harvard.edu
Subject   st: Anova with repeated variable
Date   Fri, 25 Oct 2002 13:04:10 +0200

Dear Statalist,

I am trying to replicate with Stata the  two way Between-Within Analysis of
Variance example proposed by Keppel (Design and Analysis, 3rd ed, Table 17-6
pp 375). In this example subjects perform a digit cancellation task and
their performace on this task is measured. The between factor (a) represents
3 different motivations, and the repeated factor (b) represents four trials
on this task. Four subjects were assigned to each of the 3 conditions, and
their performance was measured on 4 trials. 

a	s		b1		b2		b3		b4

a=1 	1 2 3 4		13 10 13 4	14 11 19 12	17 15 18 14	20
14 21 15	
a=2	5 6 7 8		5 8 14 12		10 15 16 21	17 22 23 26
21 24 23 26	
a=3	9 10 11 12	13 9 14 8		24 22 22 18	28 22 28 27
30 24 28 28	

After typing :
	anova Y A/s|A B A*B, repeated(B)
I get this result :
                           Number of obs =      48     R-squared     =
0.8617
                           Root MSE      = 3.27094     Adj R-squared =
0.7593

                  Source |  Partial SS    df       MS           F     Prob >
F
 
-----------+----------------------------------------------------
                   Model 	|    1800.375    20    90.01875       8.41
0.0000
                        	 |
                       A	 |     414.125     2    207.0625      17.98
0.0007
                    s|A 	|     103.625     9  11.5138889   
 
-----------+----------------------------------------------------
                       B 	|  1152.41667     3  384.138889      35.90
0.0000
                     A*B	 |  130.208333     6  21.7013889       2.03
0.0964
                         	|
                Residual 	|     288.875    27  10.6990741   
 
-----------+----------------------------------------------------
                   Total |     2089.25    47  44.4521277   

However, the ANOVA table reported by is the following :
		Source		SS		df		MS
F
		A		414.13		2		207.07
6.17
		S/A		302.12		9		33.57
		B		1,152.42		3
384.14		114.67
		A x B		130.20		6		6.48
6.48
		B x S/A		90.38		27		3.35
		Total 		2,089.25	47

Can anyone tell me why I don't obtain the same error terms.
Sincerely yours,

Xavier VIVIAND, M.D.

		





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