Stanines

A stanine is a type of standardized score, used to compare the position of a single score to a distribution of scores, on a scale of 1–9. Like other standardized scores, such as percentiles, T scores, and z scores, stanines are derived from a transformation of raw scores based on an assumption of normally distributed data. Stanine is an abbreviation of “standard nine” and is obtained by dividing a normal distribution into nine intervals, with a mean of five and a standard deviation of two. This scaling results in nine equal interval segments, each of which is half a standard deviation wide, except at each end of the distribution. The mean and median of the standard distribution is located at the center of stanine 5.

Stanines ...