Reliability and validity of ratio developmental quotients from the Cattell Infant Intelligence Scale.

The test-retest reliability and predictive validity of developmental quotients (DQs) derived from the Cattell Infant Intelligence Scale as administered to children with mental retardation over 30 months of age was assessed. When DQs of 36 children assessed twice with the Cattell were compared, scores were highly correlated, with no significant difference between them, indicating impressive test score stability. When DQs of 47 youngsters assessed once with the Cattell and once with the Stanford-Binet, Form L-M, were compared, scores were significantly correlated but significantly discrepant. These results were compared to previous findings (Goldstein & Sheaffer, 1988) on the Bayley Scales of Infant Development as a predictor of Stanford-Binet IQ. The DQs derived from the Bayley were superior to Cattell DQs in predicting Stanford-Binet IQ.