Page 83 - Quantitative Data Analysis

Quantitative Data Analysis
Simply Explained Using SPSS

Example # 1

Participant Pretest Posttest Difference (D)

1 75 88 88 – 75 = 13
2 80 83 83 – 80 = 3
3 91 89 89 – 91 = -2
4 90 99 99 – 90 = 9
5 72 92 92 – 72 = 20

Mean 81.6 90.2 8.6

SD 8.62 5.89 8.56

Suppose we were interested in testing whether there is a significant
difference between the posttest and pretest means for the students.

t obs
( ) ( )
√

t obs

t obs

The t critical value at α=.05 (two-tailed, df = 4) is 2.776 which is
higher than the t obs value (t cric>t obs; 2.776 > 2.246). Thus, we will fail
to reject the null hypothesis. The research conclusion is that there is
no significance difference in the mean scores of student between
pretest and posttest.

The Theory and Applications of Statistical Inferences 67