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Time spent in formal education and training is perhaps the most widely used measure of human capital investment. Based on this measure, to what extent does the GED stimulate human capital investment among non-high school graduates? Surveys conducted by the GED Testing Service in 1980 and 1989 asked examinees to estimate how much time they spent preparing for the test. Their responses are shown in table 5.
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In 1980, GED examinees spent a median 20 hours (and $10) preparing for the test. By 1989, they were spending a median 30 hours in preparation. This change was driven by a large increase in the proportion of candidates who spent over 100 hours preparing for the test--from 11.8 percent to 24.2 percent.
We do not know what accounts for the increase at the top of the range. We considered the possibility that immigrants, who tend to persist in adult education programs,[18] comprise an increasing share of test takers. However, in 1993, immigrants made up only 7 percent of GED examinees. So small a proportion could not account for much of the observed increase in preparation time. Another possibility is that in 1989 the GED was perceived by prospective examinees as more difficult than in the past. The writing sample had been introduced as part of the battery in 1988, and the number of examinees dropped in 1988 and especially in 1989, perhaps out of hesitation at taking the revised GED. This hypothesis gains some support from a Wisconsin study (Martin 1992) which found that after the state increased its GED cut score to 40 and 50, reported preparation time for the tests increased and performance in postsecondary institutions improved.
Although a median 30 hours is a very modest amount of preparation time, the increase in the proportion of examinees who spent more than 100 hours preparing for the exam is noteworthy. According to some researchers, an adult learner needs approximately 100 hours of instruction to achieve a one-year gain in reading ability (Mickulecky and Lloyd 1993).
Nevertheless, these investments of time are still much smaller than the estimated 410 hours spent on a high school's core curriculum in a typical school year.[19] In 1995, GED test takers had completed a mean 9.9 years of school (GED Testing Service 1996a). With 2.1 additional years of schooling, high school graduates had 861 more hours of core curriculum than GED examinees, on average.[20]
In assessing the GED as a stimulus to human capital investment, note that the skill deficit that helps drive test preparation is the difference between one's existing skills and the skills needed to pass the test battery, not to excel on it. It seems plausible that if the links between GED scores and rewards were strengthened, prospective examinees would be motivated to work harder for higher scores.[21] At least one state, South Dakota, is considering designating several levels of GED attainment, based on the scores.
Because the GED takes so much less time and effort than a high school diploma and may appear to have the same status, some researchers believe that it serves as a disincentive to human capital investment, encouraging marginal students to drop out of school or facilitating their departure through a process of negotiation (Quinn 1997a, Fine 1991). Minimum GED Test taking ages in some states are consistent with this possibility. As of 1985, 5 states had set the minimum age at 16 and another 10 had a minimum age of 17. A decade later, 12 states permitted test taking at age 16, and another 12 percent permitted it at age 17 (GED Testing Service 1996a). Currently almost half of the states allow young people to take the test before the age at which they would ordinarily graduate from high school.
Further, ACE's Commission on Educational Credit and Credentials has permitted school systems in seven states to set up in-school dropout prevention programs leading to GED certification. The commission waived its policy of prohibiting the administration of GED tests to youth currently enrolled in high school. The waiver was granted on a trial basis and subject to conditions. The number of participating states has changed over time (at least one has withdrawn), but some programs are still active.
Critics believe that such arrangements appeal both to frustrated youngsters who dislike school and to frustrated teachers and administrators, who would rather focus their energies on more receptive students. In this view, alternative GED-oriented programs may help the educational system function more efficiently, but they work to the long-run detriment of the students who are channeled out of the regular high school curriculum.
We do not know whether the GED encourages high school students to drop out; there are no controlled studies on the subject. We examined the research on reasons for leaving school and found that alienation from school (expressed in different ways) was the reason most commonly given, both by dropouts in general and by GED examinees (Rumberger 1987, Ladner 1987, Baldwin 1991). Desire to work was also an important factor in males' decisions to leave and pregnancy and marriage were important in females' decisions. However, there was no information on whether the prospect of attaining an alternative credential was among the reasons for dropping out.
We also examined data on the probabilities of attaining a GED within a year or two of leaving school. If the chances were relatively high--say greater than 50/50--the prospects of getting a GED in the near future might encourage marginal students to leave. Data from the National Educational Longitudinal Survey (NELS) indicate that 18.7 percent of 8th-graders in 1988 had not graduated with their class by August, 1992 (U.S. Department of Education 1996d). Table 6 shows the credential status of these noncompleters almost two years later, in the spring of 1994.
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An estimated 14.3 percent of those who did not graduate with their class had earned a GED by graduation time in 1992, and 12.8 percent earned the credential over the next two years. By this estimate, a student who dropped out of high school had more than one chance in four (.271) of getting a GED within several years. The prospects of earning a GED in the near term are not great, but they are not trivial, either. These data, while interesting, do not provide much help in answering the question.
We also examined the age distribution of GED test takers over time. If there were a marked increase in the proportion of young examinees during the period when states were reducing the minimum test-taking ages, it might indicate that marginal students were responding to increased opportunities to take the test. Between 1985 and 1996 there was an irregular increase in the proportion of dropouts aged 19 and younger who took the GED, from 33 percent to 39.5 percent (U.S. Department of Education 1996c, GED Testing Service 1997). However, the increase is part of a pattern of fluctuations over a longer period. Since 1974 the proportion of examinees age 19 and younger has risen and fallen within a range of 31 percent to 40 percent. Once again the data provide no clear answers. In sum, the research literature does not tell us whether the GED encourages dropping out of school.
The GED was designed to measure the ability to understand, evaluate, and manipulate concepts and information and to use knowledge and reason to reach conclusions in five subject areas. Underlying performance in each of these areas is a set of basic cognitive skills that is the primary determinant of the scores on all five. The underlying cognitive skills are reflected in intercorrelations among the tests ranging from .64 to .82 (GED Testing Service 1993a).
A traditional measure of cognitive skills is the common variance among aptitude test scores, reflecting the thinking ability that allows individuals who score well on one test also to score well on others. This ability is the result of both nature and nurture and is positively related to schooling. Baldwin et al. (1995) found a correlation of .78 between a general GED factor and a general National Adult Literacy Survey (NALS) factor. In two analyses, Means and Laurence (1984) found correlations of .75 and .79 between mean GED subtest scores and the military's Armed Forces Qualification Test (AFQT) scores.[22] Correlations between total GED scores and totals on other tests are also strong, as illustrated in appendix tables B-1 and B-2. In local administrations, the GED has shown correlations of .88 with its progenitor, the Iowa Test of Educational Development; .80 with the American College Test (ACT); .81 with the Adult Performance Level (APL) Survey; .77 with New York's Degrees of Reading Power (DRP) Test; .66-.68 with the Test of Adult Basic Education (TABE); and .61-.67 on the General Aptitude Test Battery (GATB). Correlations such as these provide evidence that the GED and the other tests are measuring a common core of cognitive skills.
Another way of determining the GED tests' ability to measure and assess cognitive skills is to compare the performance of GED recipients with that of high school graduates and dropouts on other tests. Several studies have made it possible to do so, relying on the National Adult Literacy Survey (NALS) and the Armed Services Vocational Aptitude Battery (ASVAB).
The National Adult Literacy Survey (NALS), sponsored by the National Center for Education Statistics (NCES) and conducted by the Educational Testing Service, was administered in 1992 to a representative sample of approximately 13,600 individuals aged 16 and older. The survey was designed to measure three types of literacy-prose, document, and quantitative-based on understanding of such everyday materials as news stories, maps, bus schedules, checkbooks, menus, and the like. Identification of GED recipients among the NALS test takers in the survey made it possible to compare their performance with that of high school graduates and dropouts (Kirsch et al. 1993). In a second study conducted jointly by the GED Testing Service and the Educational Testing Service, a national sample of GED examinees was administered the NALS, once again permitting comparison of GED recipients and high school graduates (Baldwin et al. 1995).
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Table 7 shows the mean NALS test scores of GED recipients and high school graduates, both without further education, and of dropouts. It also shows the scores of all GEDs and all high school graduates, including those with further education, and the scores of the adult population in general.
Kirsch et al. (1993) demonstrated that GED recipients without further education scored as well on the NALS as high school graduates without further education. Our own calculations based on Kirsch's data show that dropouts have much lower NALS scores than either GEDs or high school graduates with no additional education. Passing the GED sharply distinguishes these recipients from other dropouts in terms of literacy.
Larin (1994) observed that this comparison between high school graduates and GEDs without further education does not show that GEDs have literacy proficiencies similar to those of high school graduates in general. Because most graduates have at least some college, while most GEDs do not, the comparison shows that most GED recipients score as well as the minority of less skilled high school graduates who do not go on to college.
However, table 7 shows that if we remove the restrictions on level of education, the scores of GED recipients are still similar to those of high school graduates, except in quantitative proficiency, and well above those of adults in the general population.
NALS scores, ranging from 0 to 500 on each test, are classified in five proficiency levels: Level 1 (0-225); Level 2 (226-275); Level 3 (276-325); Level 4 (326-375); and Level 5 (376-500). On average, all GED recipients and all high school graduates score a little below the mid-point of NALS' Level 3 proficiency (300). Adults in general score at the high end of Level 2. Typical NALS tasks that the average GED and high school graduate could perform include writing a brief letter explaining an error made on a credit card bill and using a calculator to figure the difference between the regular and sale price in an advertisement (Kirsch et al. 1993).
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According to the National Education Goals Panel (1993), scores at Level 3 and above represent "the range of complex literacy tasks that the ... panel considers important for competing successfully in a global economy and exercising fully the rights and responsibilities of citizenship. " Table 8 shows the percentage of GED recipients in the 1993 GED/NALS administration and the percentages of other adults at various education levels who scored at Level 3 or above on the NALS.
Two thirds of the GEDs in Baldwin's 1993 administration of the NALS (including those who would later go on to college) scored at Level 3 or above on the prose and document tests, about the same proportion as other NALS test takers with some college, and more than those with high school diplomas only.[24] On the quantitative test, 57 percent of GEDs scored at Level 3 or above, still more than high school graduates, but less than the proportion of those with some college.[25] Most GEDs, then, met the goals panel's standard for the skills essential to economic competitiveness and the exercise of civic responsibilities.
In a multiple regression analysis of state-level NALS data (Reder 1994) found that GED recipients had higher literacy scores than other dropouts on the Oregon Literacy Survey, but lower scores than high school graduates. Reder's high school graduates included those who had some postsecondary education but no degree. The reasons for the difference between Reder's findings and those above are not clear, but the difference may be due to the fact that his was a state, rather than a national, survey or to the multivariate nature of his analysis.
In any case, the national NALS data indicate that the GED clearly discriminates between the literacy abilities of recipients and those of other dropouts, that GED recipients perform as well as high school graduates, and that they perform better than adults in general.
The Armed Services Vocational Aptitude Battery (ASVAB) is used by the military to screen applicants for entry to the armed services and to assign new recruits to occupational training. It consists of 10 subtests, 4 of which measure verbal and quantitative skills, and 6 of which measure aptitude for various occupational fields. The four math and verbal subtests (arithmetic reasoning, mathematics knowledge, word knowledge, and paragraph comprehension) comprise the Armed Forces Qualification Test (AFQT), which is used in selecting enlistees. The other six tests, designed to measure such things as electronic and mechanical comprehension, help military personnel specialists place new recruits in appropriate occupational training.
Participants in the National Longitudinal Survey of Youth (NLSY) were administered the three-hour ASVAB in 1980. Earlier they had provided detailed survey information about themselves, including their level of educational attainment. Thus it is possible to compare the ASVAB scores of GED recipients with those of high school graduates and dropouts. First interviewed in 1979 at ages 14_21, the survey participants were reinterviewed in subsequent years through the time of this writing.
Four research studies--Cameron and Heckman (1993), Cameron (1994), Garet, Jing, and Kutner (1996), and Maloney (1993)--have compared the ASVAB scores of GED recipients, high school graduates, and high school dropouts, using data from the NLSY. Cameron and Heckman studied samples of male participants using 1979-87 NLSY data, and Cameron focused on females using 1979-89 data. Garet, Jing, and Kutner analyzed data for both males and females for the period 1979-92. Maloney's study focused on women ages 23-31. Although these follow-up periods differ, the studies all examined survey participants who were aged 15-22 when they took the ASVAB in 1980.
Among males, Cameron and Heckman found that high school graduates with no further education performed better on the AFQT than did GED holders, who in turn had higher scores than high school dropouts (table 9). The scores of GED recipients were closer to those of high school graduates than to those of dropouts. Cameron's findings for females were similar, although their mean scores were lower than those of males.
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Garet, Jing, and Kutner created four factors from ASVAB test scores-math reasoning, verbal ability, processing speed, and mechanical knowledge. Their analyses showed that both male and female high school graduates scored better on all four factors than did GED graduates (see appendix table B-3). The GED recipients, in turn, scored better than high school dropouts on all the factors. Once again, the scores of GED recipients were closer to those of high school graduates than to those of dropouts. The authors also found that high school graduates who entered college directly had the highest scores, followed by those who delayed entry to postsecondary education, followed by GED graduates. The differences between GED recipients and high school graduates were greatest in the area of mathematical reasoning (Garnet et al. 1996).
Maloney combined ASVAB subtests that tapped reading, math, and science aptitudes into a single measure of ability and then compared the composite scores of female GEDs, high school graduates, and dropouts. His results were similar to those in the other studies. GED women were just .03 standard deviation units above the mean for the entire sample. Female high school graduates were .27 SDUs above the mean, and dropouts were .69 SDUs below it.[26]
In comparing the scores of GED recipients and high school graduates without further education, it is not clear why GEDs had better relative performance on the NALS than on the ASVAB. Garet et al. speculated that the difference occurred because the ASVAB contains more items that tap knowledge of traditional high school curricula, such as algebra, geometry, and trigonometry. A related possibility is that the ASVAB includes more questions that tap higher-order thinking skills. Further research would be necessary to test these hypotheses.
Judging from performance on these two tests, it is evident that the GED process sorts out non-high school graduates whose cognitive skills exceed those of dropouts in general. GEDs are at least equal to high school graduates in terms of literacy, as measured on the NALS. As measured on the ASVAB, their cognitive skills are not equal to those of graduates, but they are closer to the skills of graduates than to those of dropouts. On the AFQT and ASVAB, the performance of GED recipients in math is not as strong as their performance in other areas. It may be that it is difficult to learn specific math skills outside a formal educational program.
[Functions of the GED (part 2 of 2)]