New black white IQ (g) comparison study

Bias in intelligence testing, particularly black-white IQ differences, has been a contentious area of study in the field of intelligence. A new study by Edwards and Oakland (reference, abstract, select findings, and article link provided below) adds new information to this area of study.

Briefly, using the K-12 (school-age) standardization data from the Woodcock-Johnson--Third Edition (WJ III; conflict of interest disclosure: I'm a co-auther of the WJ III), Edwards and Oakland examined, across blacks and whites, (a) the similarity of the structure of g (general intelligence), (b) mean differences in general intelligence, and (c) the similarity in predictive validity (do the WJ III g-scores predict achievement similarily across both groups). Given my potential conflict of interest, I'm only going to report the abstract and select direct quotes from the article. Readers are encouraged to read and digest the complete article.

The one comment I will make is not specifically WJ III related, but is theory related. Consistent with Carroll's (1993) conclusion that the structure of cognitive abilities is largely the same (invariant) as a function of gender and race, Edwards and Oakland's findings indicate that the structure of g (general intelligence), when operationalized by seven different CHC ability indicators (Gf, Gc, Glr, Gsm, Gv, Ga, Gs), is similar across whites and blacks.

Edwards. O. & Oakland, T. (2006). Factorial Invariance of Woodcock-Johnson III Scores for African Americans and Caucasian. Journal of Psychoeducational Assessment, 24 (4), 358-366. (click here to view)

Abstract

• Bias in testing has been of interest to psychologists and other test users since the origin of testing. New or revised tests often are subject to analyses that help examine the degree of bias in reference to group membership based on gender, language use, and race/ethnicity. The pervasive use of intelligence test data when making critical and, at times, life-changing decisions warrants the need by test developers and test users to examine possible test bias on new and recently revised intelligence tests. This study investigates factorial invariance and criterionrelated validity of the Woodcock-Johnson III for African American and Caucasian American students. Data from this study suggest that although their mean scores differ, Woodcock-Johnson III scores have comparable meaning for both groups.

Select author conclusions from the article

• Results from factor analysis, SEM, congruence coefficients, correlations coefficients, and Fisher’s Z statistic are uniform in indicating the factor structure of the WJ III is consistent for African Americans and Caucasian Americans.

• The high congruence coefficient of .99 suggests the g factor structure is essentially identical for African Americans and Caucasian Americans. In addition, all fit indices are > .95, indicative of excellent fit and suggests covariant structural equivalence between the two groups. Although the mean IQs for the groups differ, the WJ III scores from the Cognitive Battery have comparable meaning for African American and Caucasian American students. Additionally, correlations between GIA and three achievement clusters and nine achievement subtests are similarly high and statistically significant for both groups.

• The collective findings from this and other studies using the WJ III provide some support for Carroll’s (1993) assertion that CHC theory, one that forms the theoretical basis for the WJ III, is essentially invariant across racial/ethnic groups.

• Thus, when using the WJ III Cognitive with African American and Caucasian American students, practitioners can be somewhat assured that possible score differences reflect differences in the underlying latent constructs rather than variations in the measurement operation itself (Watkins & Canivez, 2001).

Technorati Tags: psychology, educational psychology, school psychology, neuropsychology, WJ III, Woodcock Johnson, race, IQ scores, IQ score differences, g, general intelligence, bias, test bias, psychometrics, cognition, cognitive, Jack Carroll, genetics, race differences