Paired Samples T-test
A statistical test used to compare the means of two related or matched groups.
What is Paired Samples T-test?
The paired-samples t-test (or dependent t-test) calculates the difference between paired observations and tests whether the mean of these differences is significantly different from zero. It is used when the same subjects are measured twice (repeated measures) or when subjects are matched on specific criteria.
Why Paired Samples T-test Matters
By accounting for the correlation between paired observations, this test isolates the effect of the intervention or condition, reducing the impact of individual differences (noise) and thus increasing statistical power.
Example
A clinical researcher uses a paired-samples t-test to compare patients' blood pressure measurements taken before and after a six-week medication regimen.
Common Mistakes
- Using a paired t-test when the observations in the two conditions are actually from different, unmatched subjects.
- Assuming the test assesses the variance of the two separate groups rather than the variance of the difference scores.