Question

Problem 4: Please use the paired difference test to solve this problem given the following conditions (5 points).

Employee #	Before (1)	After (2)	Difference Di
1	8	11
2	7	5
3	11	19

Answer 1

Employee #	Before (1)	After (2)	Difference Di	Di - Mean	^2 of Di-Mean
1	8	11	-3	0	0
2	7	5	2	5	25
3	11	19	-8	-5	25
		Total	-9		50

mean difference ¯d = -9 / 3
= -3

standard deviation of the differences sd  = 50/3 = 16.667 =   = 4.082

standard error of the mean difference, SE( ¯d) = sd / √n
= 4.082 / √3
   = 2.357

t-statistic T = ¯d / SE( ¯d)
   = 3 / 2.357
   = 1.273