Bivariate inductive statistics - ordinal and binary variables - dependent groups

Sign test (paired)

Sign test provides a hypothesis test of the difference between population medians for a pair of random samples. The null hypothesis specifies that difference between medians equals 0. The terminology, sign test, reinforces the point that the data are converted to a series of pluses and minuses. The test is based on the number of pluses that occur. Zero differences are thrown out, and the sample size is reduced accordingly.

Example: Evaluation of the improvement in aerobic fitness for 15 subjects where measurements are made at the beginning of the fitness program and at the end of it.