The Nonequivalent Health of High School Equivalents

Over 17 million adults have earned the General Education Development (GED) diploma since its inception (American Council on Education 2009). In recent years, over half a million GEDs have been awarded annually, representing over 10% of all secondary degrees (Snyder and Dillow 2011; Heckman, Humphries, and Mader 2010). The GED is referred to as the high school equivalency diploma, under the assumption that GED recipients have comparable knowledge and skills as regular high school graduates. For instance, the Census and the National Center for Education Statistics do not distinguish the GED and high school diplomas in tabulating the educational attainment of U.S. adults. Over the past two decades, however, education researchers and econometricians have accumulated persuasive evidence that the GED is associated with significantly worse labor market outcomes compared to high school diplomas (Cameron and Heckman 1993; Tyler 2003; Heckman and LaFontaine 2006; Heckman, Humphries, and Mader 2010; Heckman and Rubinstein 2001; Murnane, Willett, and Boudett 1997). In employment rates, wages, and other economic indicators, adults with a terminal GED were often found to be comparable to high school dropouts rather than regular high school graduates. In population health research, much attention has been paid to the gradients in health outcomes by education in general (Ross and Mirowsky 1999; Herd 2010; Mirowsky and Ross 2003). Little is known, however, about how the two secondary credentials, GED and a regular high school diploma, translate into adult health. Is it justifiable to consider GED recipients as equivalent to high school graduates in terms of health? The health gradient literature would suggest so: different levels of education are known to be associated with correspondingly different levels of health; we could assume that two equivalent educational credentials might be associated with equivalent levels of health. Among the few papers that compared the two secondary-schooling credentials, however, there is some disagreement. A 2005 study of about 2,000 adults aged 40–45 found no significant differences between HS and GED with respect to self-reported and physician-reported illnesses (Caputo 2005). In contrast, a recent paper using a nationally-representative sample of adults aged 25 and above found that GED recipients had higher mortality than HS graduates, especially among younger birth cohorts (Rogers et al. 2010). For emotional health, GED was found associated with higher rates of depressive symptoms compared to a regular diploma among inner-city youth (Ou 2008). Ours is the first study to focus in depth on the general health among HS graduates and GED recipients. These two groups represent millions of U.S. adults who are assumed to be comparable in their skills and thus presumably also obtain equivalent returns to their credentials in terms of outcomes like health. THE GED AND ITS RECIPIENTS The GED is an examination-based credential, consisting of five tests (science, reading, writing, social studies and science/mathematical skills). The credential is intended to certify that its recipients have cognitive skills and knowledge comparable to those of high school graduates (Heckman, Humphries, and Mader 2010; Tyler 2005). The GED was created in 1942 to enable young WWII veterans who interrupted their secondary education when they enrolled in the military to complete high school requirements (Tyler 2005). Over the following decades, the proportion of young adults who completed secondary education via the GED exam rather than the high school diploma has systematically increased (Heckman 2008). In recent years, up to 18% of young adults who completed high school did so via the GED (Heckman, Humphries, and Mader 2010). In varied outcomes, GED recipients differed significantly from regular high school graduates. Although the GED is widely accepted as a satisfactory prerequisite for college admission, relatively few GED recipients enroll in and graduate from 4-year colleges (Heckman, Humphries, and Mader 2010). GED earners also appear to drop out of the military at much higher rates than conventional HS graduates (i.e., see Heckman and LaFontaine 2010; Boesel 1998). Ou (2008) examined a range of outcomes among inner-city youth, including incarceration, childbearing, life satisfaction, and substance use. She found a ‘gradient’ where high school dropouts fared worse than GED recipients, who in turn fared considerably worse than high school graduates. Caputo (2005) found a similar gradient with respect to depression in a study of mid-life adults. PATHWAYS FROM EDUCATION TO HEALTH Among the explanatory factors that link education and health outcomes, two stand out as important factors in the general literature, and specifically in the GED-HS comparison: economic status and health behaviors. The economic resources include higher income, greater wealth, and more stable employment, all of which are associated with better health (Adams et al. 2003; Backlund, Sorlie, and Johnson 1996; Elo, Martikainen, and Smith 2006; Sorlie and Rogot 1990). Health behaviors comprise a rich set of lifestyle factors: higher education is often associated with more exercise, moderate alcohol intake, less obesity, and less smoking (Cowell 2006; Lantz et al. 1998). In the economics literature, studies have consistently reported that relative to regular HS graduates, GED recipients have substantially worse outcomes in employment, hourly wages, income, and other labor-market indicators (Cameron and Heckman 1993; Heckman and LaFontaine 2006; Heckman and Rubinstein 2001; Clark and Jaeger 2006; Tyler 2005; Caputo 2005). The comparison between GED recipients and other dropouts without the credential has been more inconsistent, with some (but not all) studies reporting a significant benefit of the GED for wages and earnings (Heckman and LaFontaine 2006; Heckman, Humphries, and Mader 2010; Tyler 2003). Literature that has explicitly compared health behaviors between high school graduates and persons who have received GEDs is modest but motivates their inclusion in our analyses. With respect to smoking, high school graduates have been found to have significantly lower rates than GED earners, who were at best only marginally less likely to smoke than HS dropouts (Kenkel, Lillard, and Mathios 2006; Ou 2008; Barbeau, Krieger, and Soobader 2004). No significant differences between these three educational groups were found in being overweight (Kenkel, Lillard, and Mathios 2006). Although not traditionally conceptualized as a key health behavior, substance abuse was also reported more frequently among GED recipients than standard graduates (Ou 2008). RESEARCH QUESTIONS The study is organized around three questions: (1) How large are the differences in self-rated health (SRH) and activity limitations among persons with GED certificates and high school diplomas? (2) Can the observed gross differences be explained by health behaviors and labor-market characteristics of the GED and HS graduates? (3) Do the results hold for major demographic groups?