DEPENDENT T-TEST
Example Problem
 

A sports psychologist was interested in testing the effect of a simple relaxation technique on college basketball players’ free throw shooting accuracy. Each player was asked to shoot 20 consecutive free throws and the number of successful attempts was recorded. The players were then trained to use a simple 5 second relaxation technique while preparing to shoot a free throw. The players then returned to the court and shot 20 consecutive free throws again. The resulting data are given below:

[Download data]

Number of Free Throws Completed Per Twenty Attempts

pre post
12 13
15 15
9 11
16 15
12 15
15 18
17 17
10 12
12 13
14 17

SPSS

Recommendations: Before following these steps, screen your data for outliers and normality.

Data Editor

Run Analysis

 

Output

T-Test

Descriptive Statistics

Correlation between variables (we will not use this statistic)

t-test results

DEPENDENT T-TEST

Example Reporting of Results

Results

Table 2 presents the means and standard deviations for the pre and post-training. Because the data from the pre-training observations were logically tied to the data from the post-training observations, a dependent t-test was performed. The mean difference between the pre- and post-training scores was 1.40, which was statistically significant, t(.05, 9) = 3.10, p = .013. There was a moderate gain from the pre- to the post-training scores (g=.57).

Table 2

Mean Pre-training and Post-training and Standard Deviations

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Group Mean SD
Pre-training 13.20 2.62
Post-training 14.60 2.32

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Discussion

The results showed the post-training scores to be significantly higher after exposure to the relaxation technique. This means that the relaxation technique appears to have a positive effect on the players’ free throw shooting accuracy.