A Paired-Samples t-Test compares the means between two related groups, such as comparing the difference between pre-intervention and post-intervention test results.
It is considered a parametric test and is only suitable for parametric data. To check if your data is parametric, please check out the dedicated guide: Parametric or Not Guide (PDF)
If your data is non-parametric you should consider using a Wilcoxon Test.
Click Analyze > Compare Means > Paired-Samples T Test
Within the Paired Samples t-Test box, select the two variables you wish to analyse and move to them to the Paired Variables Box using the right arrow
Click OK
SPSS will generate three tables, for this test we need two, the Paired Samples Statistics and the Paired Samples Test.
This table shows a selection of descriptive statistics: the sample size (N), the mean of score (Mean), and the standard deviations (Std. Deviation), these are the three descriptives that are typically reported.
This table shows the specific test results including the t-statistic (t), the degrees of freedom (df) the two-tailed significance or p-value (Two-Sided p), the mean difference between the groups (which we report below using d̄), and the 95% Confidence Interval (95% Confidence Interval of the Difference).
Students’ test results were compared before and after the intervention. On average, students performed better after the intervention (M = 73.30, SD = 11.91) than before (M = 69.00, SD = 6.64). A Paired-Samples t-Test indicated this difference, d̄ = 4.30, 95%CI [0.83, 7.77] was statistically significant, t (19) = 2.60, p = .018.
