Black–White Achievement Differences and Governmental Interventions

Human-capital differences have provided a common explanation for racial earnings differences, although for data reasons most attention has focused just on differences in school quantity and has left out quality considerations. Patterns of quality change, however, fill in an important dimension of human-capital movements and at the same time relate directly to major governmental policies. Trends in cognitive achievement scores compiled by the National Assessment of Educational Progress (NAEP) provide consistent quality data since roughly 1970 for a representative sample of students across mathematics, reading, and science. Figure 1 shows the difference in white–black average performance of 17-year-olds in standard-deviation units. Although the pattern and magnitudes differ slightly by subject, the gap was roughly constant in the 1970’s, fell significantly in the 1980’s, and leveled off or increased slightly in the 1990’s. Even though the average gap remains around one standard deviation in the 1990’s, this gap is 0.3 standard deviations less than in the 1970’s. The lessening of the gap over the past three decades also appears in most other databases that allow such comparisons over time (Larry Hedges and Amy Nowell, 1998). Changes in black–white achievement gaps, particularly the narrowing in the 1980’s, have been the subject of recent investigations (Christopher Jencks and Meredith Phillips, 1998). Much of the discussion focuses on the optimistic story that can be generated by the experiences of the 1980’s and does not get to the mounting evidence of a continued sizable and unchanging gap in the 1990’s. While a variety of objective and subjective factors have been suggested, three major systematic factors offer clear possibilities for explaining the changes in black–white performance on the NAEP tests. Over the past three decades two major governmental interventions with significant racial dimensions have had enormous effects on school operations: legal actions to promote school desegregation and legislative and legal actions to change the level and distribution of school funding. However, these governmental interventions have taken place against a backdrop of significant relative changes in schooling and family size between blacks and whites. Clearly it is not possible to disentangle these influences from direct analysis of the few aggregate observations of test performance provided by the NAEP scores. The alternative approach taken here is to review evidence about the relationship between the major hypothesized factors and student performance. This evidence on marginal impacts is then combined with data on the magnitude and pattern of changes in each factor to see if the projected outcomes are roughly consistent with the aggregate changes in scores. Since changes in schooling factors operate with a lag, changes during the 1970’s have their full impact on the scores of 17-year-olds during the 1980’s, and similarly, changes during the 1980’s are felt most during the 1990’s.