Applied Statistics Lesson of the Day – The Matched-Pair (or Paired) t-Test

My last lesson introduced the matched pairs experimental design, which is a special type of the randomized blocked design.  Let’s now talk about how to analyze the data from such a design.

Since the experimental units are organized in pairs, the units between pairs (blocks) are not independently assigned.  (The units within each pair are independently assigned – returning to the glove example, one hand is randomly chosen to wear the nitrile glove, while the other is randomly chosen to wear the latex glove.)  Because of this lack of independence between pairs, the independent 2-sample t-test is not applicable.  Instead, use the matched pair t-test (also called the paired or the paired difference t-test).  This is really a 1-sample t-test that tests the difference between the responses of the experimental and the control groups.

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