WHAT A DIFFERENCE A MEASURE MAKES - PARENTAL-SEPARATION EFFECT ON SCHOOL GRADES, NOT ACADEMIC-ACHIEVEMENT

On the basis of empirical evidence that non-ability factors are more i mportant determinants of school grades than of academic achievement te st results, it is assumed that a student's social environment will aff ect grades more than scores on achievement tests. That assumption is a part of the basis for the hypothesis that parental separation will ha ve a stronger negative effect on school grades than on academic achiev ement scores. The hypothesis is tested in a data set in which Smith (1 990) found no significant effect of parental separation on academic ac hievement when parental occupation and education were controlled. The hypothesis is supported in data from 1,688 seventh- and ninth-grade st udents, showing the importance of the choice of indicators of complex concepts, such as school success, and suggesting that research which c oncentrates on academic achievement, to the exclusion of grades, may u nderestimate the effect of parental separation on academic success.