stanine

Grades are reported in terms of the stanine.

However, because all stanines are integers, two scores in a single stanine are sometimes further apart than two scores in adjacent stanines.

Using an expected value of 3 and a standard deviation of 1, transformations into other statistical measures like Percentiles, T, Stanine etc. or (like in the PISA studies) an IQ scale are then possible.

Promoted to Chief of the Psychological Research Unit at the U.S. Army Air Forces Training Command Headquarters in Fort Worth, Guilford oversaw the Stanine (Standard Nine) Project in 1943, which identified nine specific intellectual abilities crucial to flying a plane.