Bell Curve

146 Cognitive Classes and Social Behavior Schooling 147a ten-point gap in IQ between dropouts and high school graduates.9notherstudy, in 1949, of 2,600 students who had been given an 1Q testin the seventh grade, found a gap between the graduates and nongraduatesof about thirteen IQ points, close to the IQ's standard deviationof 15." The proportion of students getting a high school diploma hadreached about 55 percent by then. By the spring of 1960, when 70 percentof students were graduating, the data from Project TALENT-thelarge, nationally representative sample of high school students mentionedin Chapter 1-indicate a gap equivalent to almost sixteen IQpoints between the academic aptitude of those who graduated and thosewho did not, slightly more than a standard deviation.'"' This is tantamountto saying that the average dropout had an IQ that put him at the15th centile of those who graduated.The situation seems to have remained roughly the same since then. Bythe standard current definition of the population that "gets a high schcmleducationn-meaning either a diploma or by passing an equivalency examination-theNLSY data reveal that the mean score of those who geta high school education is 1.28 standard deviations higher than thosewho do not. Comparing those who get the ordinary high school diplomawith all those who left high school before doing so (including those wholater get an equivalency certificate), the gap is 1.02 standard deviations.WHITE HIGH SCHOOL DROPOUT IN THE NLSYWho drops out of high school these days? The following tahle showsthe story for NLSY whites in the various cognitive classes. The resultsFailure to Get a High SchoolEducation Among WhitesPercentage Who Did NotGraduate or Pass a HighCognitive Class School Equivalency ExamI Very bright 0I1 Bright 0"111 Normal 6IV Dull 35V Very dull 55Overall average 9" The actual figure was 0.4 percent.could hardly be starker. Among whites in the top quartile (Classes I and11 together), virtually everyone got a high school education. In the bottomquartile of the IQ distribution (Classes IV and V together), 39 percentof whites did not."*' This huge discrepancy is also predictable,however, given the close relationship between IQ and educational attainment-~~predictable that we should pause for a moment beforeviewing dropout rates with alarm. Is a 39 percent dropout rate for studentsin the lowest quartile of IQ "high"? From one perspective, it seemsso, considering how essential education appears to be for making a living.From another perspective, it is remarkable that over 60 percent ofwhite youths with IQs under 90 did get a high school education. It isparticularly remarkable that nearly half of the youths in Class V, withIQs of 75 and under, completed a high school education, despite beingon the borderline (or beyond) of the clinical definition of retarded.''3'Whether these figures say something about the ability of low-IQ studentsto learn or about the state of American secondary education is atopic we defer until Chapter 18.What Does "A High School Education" Mean?The standard question now arises: To what extent are we looking at aneffect of cognitive ability, and to what extent are white children frompoor socioeconomic backgrounds being shunted out of the school systembecause of their backgrounds? The answer depends on exactly how thequestion is asked. Specifically, it is important to be precise about what "ahigh school education" means. In the table above, it was defined to includeanyone who graduated from high school in the normal way or whopassed an equivalency examination, known generically as a GED (forGeneral Educational Development).14 This has become nearly standardpractice when researchers and journalists alike talk about high schooldropout. But recent work by economists Steven Cameron and JamesHeckman has demonstrated that GED youths are not equivalent tol'normal"graduates in terms of their success in the job market.15 In their unemploymentrates, job tenure, and wages, the GEDs look more likedropouts than they look like high school graduates, raising the possibilitythat they differ from other high school graduates in a variety of waysthat makes it dangerous to lump all people with "a high school education"into a single group. We know from our own analyses that the whiteGEDs in the NLSY had an average IQ half a standard deviation lower