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|Table of Contents Statistical Tests Means Paired Experiments|
|See also: hypothesis testing, survey on statistical tests, comparing means, distribution calculator|
Assumption: the distribution of the differences is normal and the differences are a random sample.
The paired difference experiment is often more powerful, since it can eliminate differences in the samples that increase the total variance, s2. When the comparison is made between groups (of similar experimental units), it is called blocking. The paired difference experiment is a simple example of a randomized block experiment.
NOTE: The blocking has to be done before the experiment is performed.
When the normality assumption is not fulfilled, one can use the non-parametric
Wilcoxon sign rank test for paired difference designs.
Last Update: 2005-Jul-16