ts, and different researchers tend to include a wide variety of variables in their own definitions of socioeconomic status. Another identi fied problem in this research area is that researchers do not employ a uniform approach in the measurement of variables. Some researchers use an aggregate approach, in which all stu dents in a particular school, a particular neighborhood, or so forth are assigned to the same socioeconomic group, and in which aggregate academic achievement is used in place of individual student achievement. Other researchers, by con trast, measure both socioeconomic status and academic achieve ment on an individual student basis. Still other researchers employ what is sometimes described as a confounding approach, in which either socioeconomic status or academic achievement is measured on a individual student basis, while the other vari able is measured on an aggregate basis.
It has also been found that a wide range of internal validity exists among the different research studies reporting 3on the achievement/socioeconomic status relationship. This range is due to the ways in which measurements are obtained. As an example of internal validity differences, consider the measurement of parental educational attainment, one of the principal factors generally included in the definition of socioeconomic status. Some researchers interview parents to ascertain their educational attainment, while others accept the word of students as to parental educational attainment, while still others accept the estimates of teachers as to parental educational attainment. In some instances, researchers accept the estimates of central school administrative officers as to the mean levels of parental educational attainment within dif ferent schools.
It has been found that the median correlation between socioeconomic status and academic attainment, when aggregate data are used, is far higher than the median correlation found whe...