Bell Curve

148 Cognitiue Classes and Social Behavior Schooling 149than the average for white high school graduates. Furthermore, apartfrom the specifics of the data, it is apparent that the nature of the GEDstudent's behavior--giving up on school, then later returning to pass theexamination-is different in kind from that of both the dropout wholeaves school and never goes back, and from that of the youth who stickswith four consecutive years of schooling and gets a diploma.To clinch their case for separating GED from "normal" graduates,Cameron and Heckman also point out that the size of the GEDpopulation, once negligible, has grown to become a substantial minority.In 1968, GED graduates accounted for only 5 percent of all highschool certifications. By 1980, that proportion had reached more than13 percent, where it has remained, with minor fluctuations, ever since.'16'We are persuaded that these disparate groups need to be separatedand will therefore analyze separately the relationship of IQ and socioeconomicbackground to each of these two types of dropouts.In predicting which white youths will never complete ahigh school education, IQ is more important than SESProbability of permanently dropping out of high school708 -The Permanent DropoutsFirst, we compare students who got a high school degree through thenormal process with dropouts who left school never to return, shown inthe next figure.Staying through high school to receive a diploma did not requiregenius or high-status parents. Dropout rates were extremely low forwhite students who were of at least average intelligence or socioeconomicbackground. But dropout rates rose rapidly when those variablesfell below average, with the rise being precipitous for studentswith low IQ.A closer look at these numbers dispels the stereotype of the highschool dropout as the bright but unlucky youngster whose talents arewasted because of economic disadvantage or a school system that cannothold onto him-the stereotype that people have in mind when theylament the American dropout rate because it is frittering away the nation'shuman ~a~ita1.l'~' Among whites, hardly anyone in the NLSY fitthat description. Of the whites who dropped out never to return, onlythree-tenths of 1 percent met a realistic definition of the gifted-but-disadvantageddropout (top quartile of IQ, bottom quartile of socioeconomicbackground.) Another eight-tenths of 1 percent were in the topquattile of IQ and the third quartile of the socioeconomic distribution.Very low(-2 SDs)Very high(+2 SDs)Note: For computing the plot, age and either SES (for the hlack curve) or 1Q (for the graycurve) were set at the~r mean values.Even when we relax the definition to include everyone who is from thetop half of the IQ distribution and the bottom half of the socioeconomicdistribution-a very loose definition indeed-we are talking about agrand total of only 5.5 percent of the permanent dropouts, or half of 1percent of American whites in the NLSY."~'The permanent dropout instead fits the older image, more commonamong the general public than intellectuals, of the youngster who isboth not very smart and from the wrong side of the tracks. To put ittechnically, the effects of socioeconomic status and intelligence interact.A white youth who had both low cognitive ability and a poor socioeconomicbackground was at even more risk of dropout than theseparate effects of each variable would lead one to expect."9' Of whiteyouths who were in the bottom quartile on both IQ and socioeconomicstatus, half permanently dropped out of school.