The Wiat-II has a standard score of 100 with a deviation of 15. A deviation is a margin of error. For this test, using standard scoring, there is an error range of 15 points. Any particular score could actually be up to 15 points higher or lower than the actual score reported. The mean or average range, for a standard score on the Wiat-II is from 90 to 110.
The scaled score has a mean of 10 with a standard deviation of three. Ten is the average score using the scaled scoring method. The average or middle range of scaled scores falls between eight and 12 using this method.
A percentile ranking is the score that most of us are familiar with. This score compares the student's score to the norm-referenced group score. When a standardized test is created, a large group of individuals with a variety of backgrounds is tested. The scores of these individuals create the set of normal scores that all other scores are compared to. For example if a student scored 65 percent on the Wait-II test, the score means that he or she performed better than 65 percent of the norm referenced group. It can be said that this student did not perform as well as 35 percent of the norm-referenced group. Any score between 25 and 75 on the Wiat-II is an average percentile score.
T-scores for the Wiat-II test have a mean or average of 50 and a standard deviation of 10. The middle range of T-scores falls between 43 and 57. Any score in that range is considered an average score.
Stanine is an acronym for Standard Nines. It is a nine-point scoring system. Scores ranging from four through six are considered average. Any score below a four is considered low-performing, and any score above six is considered well performing.