Disentangling the effects of related and unrelated employment obviously requires a definition of which occupations are matched with particular fields of study. In this analysis, I use a definition developed by Medrich and Vergun (1994), with few changes.[31] The matching algorithm, presented in Appendix B, links occupational fields of study with Census Occupation Codes contained in the SIPP data. There are relatively few broad fields of study--nineteen, plus an "other" category--of which nine are occupational. Therefore this matching algorithm should, if anything, err on the side of over-inclusiveness, by deciding that a program of study and an individual's occupation are related when in fact they may not be.
Table 6 presents information about the extent of related and unrelated employment. For individuals with baccalaureate degrees, roughly 60% have related employment. For those with Associate degrees, the proportion of related employment is lower for men but higher for women; in examining the extent of matches by occupation, this proves to be due to the especially high rate of available employment in business and health occupations, which tend to be dominated by women. The extent of relatedness among individuals with certificates hovers around 50% to 55%. Among individuals with some college but without
| 1984 | 1987 | 1990 | ||||||
| Males | Females | Males | Females | Males | Females | |||
| B.A./B.S. | 63.8% | 64.2% | 61.0% | 56.3% | 61.9% | 61.2% | ||
| Associate | 56.7 | 70.4 | 47.9 | 63.9 | 47.2 | 63.0 | ||
| Certificate | 59.5 | 68.6 | 50.5 | 54.3 | 55.3 | 55.3 | ||
| Some college, no credential: | ||||||||
| 4 years | 50.0 | 34.5 | 32.1 | 47.6 | 39.4 | 52.6 | ||
| 3 years | 53.0 | 55.4 | 50.7 | 44.2 | 44.1 | 43.2 | ||
| 2 years | 42.4 | 53.8 | 40.6 | 44.6 | 45.4 | 44.9 | ||
| 1 year | 43.4 | 56.0 | 43.7 | 52.1 | 35.2 | 50.2 | ||
| < 1 year | 32.8 | 51.2 | 40.6 | 47.8 | 33.5 | 44.1 | ||
a credential, the patterns for men suggest that those with more years of postsecondary education are also more likely to find related employment; but the patterns for women are erratic. Overall, individuals with credentials have higher rates of related employment than do those with limited amounts of college. Therefore, part of the higher economic benefits of completing coherent programs is due to the advantage that having a credential provides in finding employment related to one's field of study. Unfortunately, what remains unclear is whether these figures are "high" or "low," since there is no obvious benchmark to establish what appropriate levels might be.[32]
Tables 7 through 12 present the effects of postsecondary education, differentiated by whether an individual had related employment, unrelated employment, employment whose relationship is unknown (because the field of study was "other"), or had an academic field of study for which there was no attempt to match employment. In this profusion of coefficients, several findings stand out. First, the returns to related employment are almost always higher than the returns to unrelated employment; this is true for 44 of the 48 comparisons in these tables. This confirms the hypothesis that the job-specific nature of vocational education reduces its value in unrelated jobs. Second, while the returns to unrelated Associate and baccalaureate degrees are lower than to related degrees, they still tend to be significant; the implication is that occupational degrees do have some general components that enhance productivity and earnings even in occupations unrelated to the field of the credential. Third, in a substantial number of cases (18 of the 48 comparisons)--and particularly among individuals with some college but no credentials--the coefficient for related employment is significant, but that for unrelated employment is not. These are particularly worrisome cases because they imply that completing coursework is necessary but not sufficient to realize economic benefit and that placement in a related occupation is crucial. And, while community colleges do have mechanisms which link their programs to employers, enhancing the prospects for students to find related employment, in many cases these linking mechanisms are quite weak (Grubb et al., 1992).
Overall, these results confirm the importance of finding related rather than unrelated employment. In part, this finding helps explain the variation in returns to different fields of study, since some fields--business and health occupations, for example--have higher rates of related employment than do others; the higher returns associated with completing credentials rather than coursework without credentials is also partly due to this effect. For educational institutions and policymakers, these results confirm the value of efforts to link programs to employers and to help students find jobs related to their programs of study.
| Related Employment | Unrelated Employment | Relationship Unknown | Academic Field | |
| B.A./B.S. | .535* (.035) | .449* (.045) | .535* (.080) | .318* (.039) |
| Associate | .240* (.062) | .163* (.070) | .111 (.120) | .152 (.089) |
| Certificate | .258* (.089) | .183* (.108) | .158 (.226) | --- |
| Some college, no credential: | ||||
| 4 years | .506* (.138) | .367* (.141) | .284 (.217) | .111 (.114) |
| 3 years | .450* (.093) | .103 (.098) | .251 (.191) | .143 (.087) |
| 2 years | .247* (.068) | .135* (.059) | .031 (.106) | .116 (1.70) |
| 1 year | .187* (.064) | .067 (.057) | .129 (.097) | .146* (.068) |
| < 1 year | .177 (.113) | .133 (.081) | .102 (.136) | .126 (.101) |
| N = 7982, R2 = .339
| ||||
| *Significant at 5%, conventional 2-tailed test. Standard errors are in parentheses. | ||||
| Related Employment | Unrelated Employment | Relationship Unknown | Academic Field | |
| B.A./B.S. | .446* (.054) | .199* (.069) | .199 (.145) | .340* (.054) |
| Associate | .446* (.074) | .099 (.112) | .349* (.167) | .031 (.128) |
| Certificate | .272* (.080) | -.079 (.116) | .361 (.316) | ---- |
| Some college, no credential: | ||||
| 4 years | .236 (.284) | .436* (.209) | -.043 (.326) | .414 (.243) |
| 3 years | .276 (.165) | .000 (.181) | .811* (.342) | .269 (.167) |
| 2 years | .067 (.092) | -.040 (.100) | .238 (.171) | -.073 (.095) |
| 1 year | .242* (.078) | .047 (.088) | .275 (.164) | -.120 (.086) |
| < 1 year | .185 (.114) | -.051 (.118) | -.188 (.207) | -.130 (.142) |
| N = 6557, R2 = .308
| ||||
| *Significant at 5%, conventional 2-tailed test. Standard errors are in parentheses. | ||||
| Related Employment | Unrelated Employment | Relationship Unknown | Academic Field | |
| B.A./B.S. | .496* (.042) | .421* (.050) | .274* (.097) | .259* (.044) |
| Associate | .198* (.070) | .262* (.067)< | .232 (.123) | .128 (.104) |
| Certificate | .098 (.100) | .202* (.102) | .077 (.281) | ---- |
| Some college, no credential: | ||||
| 4 years | .768* (.230) | .168 (.160) | -.046 (.397) | .124 (.142) |
| 3 years | .617* (.116) | .024 (.118) | .370 (.309) | .063 (.111) |
| 2 years | .296* (.079) | .097 (.066) | .112 (.139) | -.017 (.081) |
| 1 year | .259* (.075) | .080 (.068) | .175 (.129)< | .129 (.083) |
| <1 year | .112 (.109) | .081 (.091) | -.005 (.145) | -.075 (.110) |
| N = 5452, R2 = .391
| ||||
| *Significant at 5%, conventional 2-tailed test. Standard errors are in parentheses. | ||||
| Related Employment | Unrelated Employment | Relationship Unknown | Academic Field | |
| B.A./B.S. | .470* (.063) | .075 (.069) | .148 (.145) | .404* (.064) |
| Associate | .550* (.085) | -.164 (.110) | .375* (.176) | .016 (.119) |
| Certificate | .295* (.101) | -.017 (.109) | .677 (.375) | ---- |
| Some college, no credential: | ||||
| 4 years | .083 (.298) | -.330 (.282) | 1.044 (.649) | -.024 (.352) |
| 3 years | .460* (.180) | .098 (.159) | .603* (.307) | .108 (.164) |
| 2 years | .356* (.119) | .038 (.108) | -.685* (.203) | .041 (.109) |
| 1 year | .349* (.094) | .004 (.098) | .164 (.143) | -.124 (.097) |
| <1 year | .305* (.140) | -.222 (.133) | .459* (.212) | -.036 (.157) |
| N = 4952, R2 = .375
| ||||
| *Significant at 5%, conventional 2-tailed test. Standard errors are in parentheses. | ||||
| Related Employment | Unrelated Employment | Relationship Unknown | Academic Field | |
| B.A./B.S. | .524* (.027) | .365* (.033 | .449* (.056) | .388* (.029) |
| Associate | .248* (.051) | .105* (.048) | .106 (.091) | .174* (.063) |
| Certificate | .039 (.059) | .113 (.065) | -.018 (.144) | ---- |
| Some college, no credential: | ||||
| 4 years | .642* (.127) | .256* (.105) | .098 (.186) | .240* (.114) |
| 3 years | .305* (.079) | .139* (.071) | .240 (.172) | .153 (.081) |
| 2 years | .201* (.048) | -.022 (.044) | .013 (.081) | .064 (.052) |
| 1 year | .228* (.057) | .069 (.043) | -.036 (.084) | .056 (.057) |
| <1 year | .150 (.084) | .033 (.060) | .051 (.106) | .085 (.080) |
| N = 10,601, R2 = .412
| ||||
| *Significant at 5%, conventional 2-tailed test. Standard errors are in parentheses. | ||||
| Related Employment | Unrelated Employment | Relationship Unknown | Academic Field | |
| B.A./B.S. | .594 (.039) | .231 (.047) | .425 (.090) | .396 (.038) |
| Associate | .387 (.053) | -.034 (.068) | -.073 (.122) | .231 (.080) |
| Certificate | .348* (.060) | .083 (.066) | .088* (.170) | ---- |
| Some college, no credential: | ||||
| 4 years | .522* (.187) | .322 (.197) | .545 (.587) | .334 (.179) |
| 3 years | .190 (.117) | .179 (.103) | .269 (.209) | -.177 (.110) |
| 2 years | .342* (.068) | .084 (.062) | .095 (.141) | .212* (.070) |
| 1 year | .118* (.058) | -.044 (.058) | .195 (.116) | .063 (.066) |
| <1 year | .166 (.086) | -.170* (.077) | .129 (.158) | .138 (.099) |
| N = 9940, R2 = .394
| ||||
| *Significant at 5%, conventional 2-tailed test. Standard errors are in parentheses. | ||||
[32] In trials using a matching algorithm developed by Rob Meyer for the NLS72 data, I defined employment as related to one's field of study if, arbitrarily, 50% or more of the courses taken were related to employment. (This matching algorithm matched courses taken, not fields of study, with employment.) With this definition, 38% of students with certificates and 33% of those with Associate degrees were in related employment; see Grubb, 1989b, Table 16.) However, differences in the definition of relatedness and uncertainty about the matching algorithm make comparisons with the SIPP results in Table 6 problematic. What was clear from the NLS72 results is that individuals leaving without a credential and individuals completing fewer courses tended to have fewer courses related to their present employment--roughly corroborating results in Tables 7-12 and indicating that individuals with small amounts of coursework are more likely to be "experimenters" than individuals who know what area of employment they intend to enter.