Many statistical tests assume that the observations in a sample are independent; in other words, that the order in which the data were collected is irrelevant. If the order does matter, then the sample is not random, and you cannot draw accurate conclusions about the population from which the sample was drawn. Therefore, it is prudent to check the data for a violation of this important assumption.

You can use the Runs Test procedure to test whether the order of values of a variable is random. The procedure first classifies each value of the variable as falling above or below a cut point and then tests to ensure that there is no order to the resulting sequence.

- The cut point is based either on a measure of central tendency (mean, median, or mode) or a custom value.
- You can obtain descriptive statistics and/or quartiles of the test variable.