Question

Calculate the difference scores for the following data from a repeated measures study. Conduct a repeated measures t-test at aplha=.05 to find whether there was a change in scores. Subject A:Pre test score=34 post test score=39. Subject B:pre test score=41, post test score=48. Subject C:pre test score=38, post test score=35. Subject D: pre test score=29, post test score=36

Answer 1

There is no difference as per statistical evidence.

Explanation:

We calculate t statistic from the formula

t =difference in means/Std error of difference

Here n1 = n2

t = (x bar - y bar)/sq rt of s1^2+s2^2

Let treatment I =X = 34 41 38 29

Treatment II Y = 39 48 35 36

X Y

Mean 35.50 39.50

Variance 81.00 105.00

H0: x bar = y bar

Ha: x bar not equal to y bar

(Two tailed test at 0.05 significant level)

N1 = 4 and N2 = 4

df=N1+N2-2 = 6

s1^2 = 81/3 =27 and s2^2 = 105/3 = 35

Std error for difference =

t = -1.02

p =0.348834

p>0.05

Since p value >alpha we accept null hypothesis.

Hence there is statistical evidence to show that there is no difference in the mean level of scores.