Differential Prediction of Academic Achievement In Elementary and Junior High School By Sex

Abstract

The purpose of this study was to examine differences in predicting achievement by sex on the Iowa Tests of Basic Skills (ITBS) from the verbal, quantitative, and nonverbal scores on the Cognitive Abilities Test (CogAT). The sample consisted of all students in Grades 2, 5, and 8 who completed both the ITBS and CogAT in the fall 1984 joint national standardization of ITBS Form G and CogAT Form 4, resulting in a sample of about 5000 boys and 5000 girls for each grade level. Examination of means and standard deviations on CogAT showed that boys and girls had similar scores on all three CogAT areas for all grades. When ITBS scores were predicted separately from each CogAT score by sex, significant differences in either slope or intercept were found between the prediction equations for several ITBS subtests, most frequently for reading and language skills. The common regression lines for each ITBS subtest and CogAT score were computed by sex and showed consistent over-prediction for boys on the reading, reference materials, and language skills subtests. Girls' scores were consistently under-predicted on these subtests. These differences occurred even though average verbal, quantitative, and nonverbal ability measures were similar for boys and girls. Educators who use differences between actual ITBS achievement and expected achievement based on CogAT scores should be aware of the differences in prediction for boys and girls.