T-Test Calculator for 2 Dependent Means
This calculator performs a paired samples t-test (also called dependent t-test), used when comparing two related measurements from the same subjects or matched pairs.
When to Use
Use the paired t-test when you have two measurements from the same subjects (e.g., pre-test and post-test) or matched pairs (e.g., twins, husband-wife pairs).
Examples
- Before-and-after measurements on the same subjects
- Comparing two treatments applied to the same subjects
- Matched pairs (e.g., left eye vs right eye)
Requirements
- Paired observations (same subjects or matched pairs)
- Differences should be approximately normally distributed
- Observations are independent of other pairs
Null Hypothesis
H₀: μd = 0 (the mean difference between paired observations is zero)
Formula
t = D̄ / (SD / √n)
Where D̄ is the mean difference, SD is the standard deviation of differences, and n is the number of pairs.
