and, of course, don't forget that credential inflation and what brint and karabel call the 'diverted dream' are in operation.
credential inflation means that it takes more to be properly credentialed for many jobs than it used to. witness, as one example, what's going on among techies who, for a long time, didn't need formal credentials per se to get into some fairly decent jobs. as the occupation professionalizes itself, however, it expands the formalized credential process which operates as a gatekeeper.
diverting dreams is the process whereby the big ten prestigious unis backed the expansion of state and community college systems in order to keep the working class out. they had been increasingly banging on the gates of the ivory tower demanding an education --and not necessarily one that would secure them a job. no, the evidence suggests that they were looking for a liberal arts, rather than technical, education.
the big prestigious schools backed expansion to divert people into vocational training to secure their proper socialization into the labor force.
so, the "class" story isn't surprising.
kelley
ps., on a related note, the general social survey registers the "lag" blip in the correlation between education in income during the 70s. usually there is a positive correlation between education and income and it rises steadily, smoothly. but there's a blip in the 70s when people got their foot in the "programming' door with a two year technical degree and made loads of money compared to colleagues who got degrees in social work, nursing, and criminal justice.