A coefficient alpha for test-retest data.
Transient errors are caused by variations in feelings, moods, and mental states over time. If these errors are present, coefficient alpha is an inflated estimate of reliability. A true-score model is presented that incorporates transient errors for test-retest data, and a reliability estimate is derived. This estimate, referred to as the test-retest alpha, is less than coefficient alpha if transient error is present and is less susceptible to effects due to item recall than a test-retest correlation. An assumption underlying the test-retest alpha is essential tau equivalency of items. A test-retest split-half coefficient is presented as an alternative to the test-retest alpha when this assumption is violated. The test-retest alpha is the mean of all possible test-retest split-half coefficients.
Green
Samuel B
SB
Division of Psychology in Education, Arizona State University, Tempe 85287-0611, USA. samgreen@asu.edu
D000339:Affect; D000704:Analysis of Variance; D015982:Bias; D003627:Data Interpretation, Statistical; D004644:Emotions; D006801:Humans; D015233:Models, Statistical; D010556:Personality Tests / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012942:Social Sciences / Q000706:statistics & numerical data