Question

Given the following data from a repeated-measures design study examining the effect of a treatment by measuring a group of 9 participants before and after they received treatment:
Participant Before After
A 8 7
B 7 5
C 6 6
D 7 6
E 9 7
F 8 5
G 5 4
H 9 4
I 7 4
a. Calculate the difference scores and MD.
b. Compute SS, sample variance, and estimated standard error.
c. Is there a significant treatment effect?

Answer 1

Answer:

MD = 2

SS = 18

SAMPLE VARIANCE = 2.25

STANDARD ERROR = 0.5

Step-by-step explanation:

Given :

A 8 7

B 7 5

C 6 6

D 7 6

E 9 7

F 8 5

G 5 4

H 9 4

I 7 4

Difference, d = Before - After

______ d

A 8 7 __ 1

B 7 5 __ 2

C 6 6 __ 0

D 7 6 __ 1

E 9 7 __ 2

F 8 5 __ 3

G 5 4 __ 1

H 9 4 __5

I 7 4 ___3

The mean of difference, MD ;

MD = Σd/ n = (1+2+0+1+2+3+1+5+3) / 9 = 18 / 9 = 2

The sum of square, SS ;

(1 - 2)^2 + (2 - 2)^2 + (0 - 2)^2 + (1 - 2)^2 + (2 - 2)^2 + (3 - 2)^2 + (1 - 2)^2 + (5 - 2)^2 + (3 - 2)^2 = 18

Sample variance, S² = SS/(N-1) = 18 / (9 - 1) = 18 / 8 = 2.25

Sample standard deviation, S = √Variance = √2.25 = 1.5

Standard Error, S.E = S / √n = 1.5 / √9 = 0.5

Test statistic : MD / S.E = 2 / 0.5 = 4

We test at α = 0.05 since no α - value is stated in the question.

Critical value at 0.05, df = 8 ;

Critical value = 2.306

Since; Test statistic > Critical value, then result is significant at α = 0.05