Norms and Scores
Scores on psychological, educational, developmental, and perceptual tests are generally interpreted by reference to norms. The primary advantage of age norms is that they are easily understood. Grade norms or grade equivalents are often used in educational and academic achievement tests. The normal curve is a statistically derived distribution and is particularly helpful for comparing a child’s score to that of other children. The normal curve is a symmetrical bell-shaped curve, in which the mean, median, and mode are identical. Norm-referenced test interpretation involves some method of examining how an individual’s test score compares to the scores of others in some known group. In order to circumvent this possible misunderstanding, measurement specialists have developed a variety of scoring systems to transform z-scores, so that all scores within normal limits will be positive.