The difference between the highest and lowest states is 22 points. 6 Comparable regional clusters are not apparent for eighth-grade public school black students, however. Black achievement is highest in Arizona, Wisconsin, Virginia, Indiana, Massachusetts, and West Virginia. At the other extreme, black mathematics achievement is lowest in Arkansas, Mississippi, Alabama, Louisiana, Michigan, and New York. Black achievement levels on the mathematics test average around 230 in these states.
Scores tend to be highest in the Midwest and lowest in the South.
Differences among states can be accounted for by a variety of factors. Since parental education has always been found to correlate strongly with children's achievement levels, some adjustment for this factor must be made before conclusions can be drawn regarding the impact of policy differences. A scatterplot of the 1992 NAEP eighth grade state-average mathematics achievement against the percentage of persons 25 years or older in the state with high school diplomas shows a clear positive relationship. It is also clear that some states do not follow the general pattern. Thus, differences among states with comparable levels of parent education are present and may be traceable to policy differences.