A comparison of matched pairs from each test group. The percentage of chance that there would be a difference in findings between groups studied even if data showed no difference in the groups. A typical statistical test for comparing two treatment methods. A group of 20 periodontal patients were treated with half of their jaw using a surgical method, the other half with chemical therapy. The results are compared using a paired T-test.
Variance is reported in squared units unlike mean values.
Measures both direction of the differences like a Sign Test, but also the extent of those differences.