We show that within the Chicago Public Schools, both the introduction of NCLB in 2002 and the introduction of similar district-level reforms in 1996 generated noteworthy increases in reading and math scores among students in the middle of the achievement distribution but not among the least academically advantaged students. The stringency of proficiency requirements varied among the programs implemented for different grades in different years, and our results suggest that changes in proficiency requirements induce teachers to shift more attention to students who are near the current proficiency standard.

Evaluating a Simple Method for Estimating Black-White Gaps in Median Wages by William Johnson, Yuichi Kitamura and Derek Neal. Published in volume 90, issue 2, pages 339-343 of American Economic Review, May 2000

The authors regress young adult wages on current age and the score of a basic skills test that was administered over ten years earlier, when respondents were preparing to leave high school and embark on work careers or postsecondary education. Controlling for this one measure of premarket skill greatly reduces the measured black-white wage gap for young adults. The authors' results suggest that the black-white wage gap primarily reflects a black-white skill gap that exists before young men and women enter the labor market. This skill gap in part reflects measured black-white differences in wealth and family background. Copyright 1996 by University of Chicago Press.