Factor structure of the McCarthy scales for school-age children with low GCIs

This study aimed to cross-validate the factor analysis of the McCarthy Scales and to determine the construct validity of these scales for children who score one standard deviation below the normative mean on general cognitive ability. The sample was comprised of 77 children aged 6 to $\text{8}\text{1}\text{2}$ with a mean General Cognitive Index (GCI) of 61.6. Principal factor analysis produced four meaningful factors which corresponded closely to four of the scales on McCarthy's battery. The present findings discourage the interpretation of the Quantitative Scale for school-age children with GCIs below 84. Other implications of the results for the interpretation of McCarthy profiles for low-scoring school-aged children are discussed.