E-ISSN : 2733-4538
Kim(1999) has proposed a method of estimating premorbid intelligence that is based on the K-WAIS norm data. The purpose of the present study was to modify Kim's method of estimating premorbid intelligence. Kim's method uses subjects' age and years of education as predictors of premorbid intelligence. The present method uses subjects' year of birth and years of education as predictors of premorbid intelligence. Ten years have passed since the standardization of K-WAIS and the scale uses 10-year interval in age-grouping. Thus, 2001 is the critical year in which use of subjects' year of birth rather than their age as a predictor of premorbid intelligence makes a real difference. The K-WAIS norm data show that of subjects with the same level of education, the mean IQ of older subjects is higher than the mean IQ of younger subjects. This difference between older and younger subjects is not related to chronological ages but to cohort differences in education opportunity. Thus, it is more valid to use subjects' year of birth rather than their age as a predictor of premorbid intelligence.