Are Race Differences in Mental Test Scores an Artifact of Psychometric Methods? a Test of Harrington's Experimental Model

Abstract

This study examines Harrington's hypothesis that blacks obtain lower mean scores on mental tests as a result of their small representation in the test development population. Two new intelligence test forms—a black form and a white form—were constructed using maximally unequal numbers of blacks and whites. Results indicated that blacks did not perform significantly better on the test form developed solely on their own item statistics. Bias in predictive validity was also investigated and noted to occur on the intercepts of some of the regression lines. These findings indicate that using equal or unequal numbers of blacks and whites in test development samples results in the same findings of little or no differential construct and predictive validity of intelligence tests across racial groups as reported in studies with tests developed using population proportionate sampling procedures. Differences in special education placement rates of black children, though related to black-white differences in mean IQs, are not due to the phenomenon described by Harrington.