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The paired t-test is a t-test that is used when the test units can be paired. For example, the blood pressure of five patients was tested before and after a medication:
|
Patient
|
Before
|
After
|
D
|
| Andrew |
120
|
110
|
10
|
| Bill |
135
|
115
|
20
|
| Charles |
110
|
110
|
0
|
| David |
140
|
135
|
5
|
| Eric |
115
|
110
|
5
|
A Two Sample t test would show no significant difference in the 'before' and 'after' results because the difference between individuals masks the 'before' and 'after' difference.
The paired test involves carrying out a One Sample t-test on the differences. Despite the variation between individuals the 'after' blood pressure is generally lower.
See also Two Sample t-Test.
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