Three-year stability of WISC-R IQs for handicapped children from three racial/ethnic groups

Score stability is an important psychometric quality of tests intended to measure relatively enduring characteristics such as intelligence. The purpose of the present study was to examine the long-term stability of WISC-R IQs (Full Scale, Verbal, and Performance) for a sample (N = 382) of male and female subjects from three racial or ethnic groups (Anglo, black, Mexican-American). The three-year stability coefficients for the varied sample of subjects (VIQ = .81, PIQ = .78, FSIQ = .85) compared well with those established with a three-week interval during the standardization of the WISC-R. Specific findings indicated that Anglo subjects' IQs were significantly more stable than those of blacks on all three IQ scales and also more stable than those of Mexican-Americans on the Performance and Full Scales. Sex of the subject had minimal influence on test score stability; only females' Verbal performances resulted in significantly larger stability coefficients than those of males. These and other results are discussed from educational, developmental, and psychometric perspectives.