Although GED recipients have the same measured academic ability as high school graduates who do not attend college, they have the economic and social outcomes of otherwise similar dropouts without certification. Despite measures of cognitive ability similar to high school graduates, GED recipients perform significantly worse in all dimensions when compared to them (Heckman and Rubinstein ). GED recipients lack noncognitive skills such as perseverance and motivation that are essential to success in school and in life. The GED opens education and training opportunities but GED recipients do not reap the potential benefits because they are unable to finish these activities. GED recipients attrite from the military at the same rate as other dropouts and they exit post-secondary schooling with nearly the same degree attainment rates as other dropouts who start with no credential.
--James Heckman and Paul LaFontaine, "The American High School Graduation Rate: Trends and Levels"