K-WAIS-IV 단축형 지능검사의 IQ 추정 오차와 보정 방안 = The systematic errors of K-WAIS-IV Short Forms and new correction proposal

국문 초록 (Abstract)

단축형 지능검사에서 회귀추정 방식으로 지능을 추정할 경우 실제IQ (전체척도IQ)가 평균보다 낮은 사람들의 IQ가 과대추정 되는 경향이 있다. 이는 일정한 방향성을 지닌 체계적 오차로 단축형 지능검사의 적절성을 위협하는 요인이다. 본 연구에서는 이러한 오차를 줄이기 위해 Davis(1976)의 RTM 에 관한 수학적 모델을 응용하여 RTM 보정 공식을 고안하였다. 본 연구는 또한 이 보정 공식의 타당성을 확인하기 위해 두 개의 동질적인 낮은 지능 집단들과 이질적 정신장애 집단을 대상으로 비례배분 방식, 선형동등화 방식, 보정 전 회귀추정 방식, Ehrler 등(2019)의 보정회귀 방식과 RTM 보정 방식의 오차를 비교하였다. 그 결과 본 연구에서 제안한 보정 공식은 보정 전 회귀추정 방식보다 뚜렷하게 개선된 정확도를 보였고, 비회귀추정 방식인 비례추정 방식, 선형동등화 방식 보다 더 나은 정확도를 보였으며, Ehrler 등(2019)이 제시한 보정회귀 방식 보다도 정확도가 높은 것으로 나타났다. 아울러 보정회귀 방식을 사용한 경우에는 추정 오차의 선형성이 관찰되었지만 RTM 보정 공식을 이용하였을 때는 이러한 선형성이 사라지는 것을 확인하였다. 이러한 결과의 시사점, 의의, 한계에 대해 상세히 논의하였다.

다국어 초록 (Multilingual Abstract)

Using regression equation for short forms of intelligence scales tends to cause over-estimation of the IQ especially for those who have lower intelligence. Such an systematic error in IQ estimation threats the validity of intelligence scale short form. The current study aims to resolve the problem by proposing new way of correction based on RTM amount formula by Davis(1976). To do so, this study compared the accuracies of proration method, linear equating method, regression formula method, regression equation correction by Ehrler et al.(2019) with our correction proposal. Two homogeneous low intelligent groups and a heterogeneous clinical group were tested. As results, the proposed correction method showed better accuracy over regression formula method, better validity over proration method and linear equating method, and more generally applicable over Ehrler et al.(2019)’s correction. The proposed correction method successfully reduced the systematic error of over-estimation for lower intelligence.

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