A two-score composite program for combining standard scores

It is often desirable for mental health practitioners to combine standard scores from different tests, raters, or times into a single composite standard score. Most often the result is a more reliable and accurate standard score. This paper describes a computer program that uses two standard scores, score reliability and correlation with a third variable, to yield a composite standard score, reliability and correlation. Trends, limitations, optimum benefits, and examples are discussed. References are provided for calculating composites based on more than two scores.