2011_SS1_Homework 06 - Solutions

# X2 3 s x1 x2 1 19 for alpha 005 the critical

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Unformatted text preview: n1 n2 10 5 Estimated standard error of the mean difference = 3 18) An independent ­measures research study was used to compare two treatment conditions with n=12 participants in each treatment. The first treatment has a mean of X1 = 55 and 2 variance s12 = 8 ; the second treatment has a mean of X2 = 52 and variance s2 = 4 . Calculate and report the value of the appropriate test statistic we would use to determine if there is an effect of treatment. NEED SS to get pooled variance if we want to use pooled variance formula. SS1 SS SS2 SS 2 s12 = , 8 = 1 " SS1 = 88 , s2 = , 4 = 2 " SS2 = 44 n1 ! 1 11 n2 ! 1 11 SS + SS1 88 + 44 2 132 s 2 ed = 1 , s 2 ed = , s pooled = , s 2 ed = 6 pool pool pool df1 + df2 11 + 11 22 OR: because n1 = n2, pooled variance will be the simple average of the sample variances, (4+8)/2, (12/2) = 6 s( X1 ! X2 ) = s 2 ed pool n1 + s 2 ed pool n2 , s( X1 ! X2 ) = 6 6 + , s( X1 ! X2 ) = 0.5 + 0.5 , s( X1 ! X2 ) = 1 12 12 t( X1 ! X2 ) = ( X1 ! X2 ) 55 ! 52 , t( X1 ! X2 ) = , t( X1 ! X2 ) = 3 s( X1 ! X2 ) 1...
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