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Intelligence tests continue to be the most widely used measures of cognitive aptitudes. Performance on such measures is usually expressed as an IQ score. Popular opinion to the contrary, relatively little is known about the long term measuring of IQ scores from group verbal and non-verbal intelligence tests, especially the latter. This study shows that, below ten years of age, stability in IQ scores from group verbal tests is considerably below that for the Stanford-Binet. Non-verbal IQ scores were found to have substantially less stability than Verbal IQs.
Hopkins et al. (Sat,) studied this question.