<p>The gap consists of people who go to top-ranked engineering programs, and flunk out. For example, those people who choose engineering at MIT or Caltech or Berkeley and flunk out would have almost certainly been far better off majoring in something else, or going to an entirely different school, or both. </p>
<p>This is incidentally why I support a policy of students being allowed to cancel bad grades in weeder classes they get that have nothing to do with the major that they are currently in. For example, if a guy goes to Berkeley EECS, gets horrible grades in the weeders, and so switches majors to, say, American Studies or something, then what do his old bad EECS weeder grades matter? After all, he's not getting an EECS degree anyway, so who cares what his grades were in those classes? The weeder classes have fulfilled their purpose by eliminating that guy from the major, so what purpose is served by tagging that guy's permanent record with a bad grade? Another method is to simply make all weeders pass/no-grade-recorded. Each student will be sent a private letter stating what their letter grade would have been if the class was graded normally, but for the purpose of the official transcript, the class is graded either P, or no grade at all is recorded if you didn't pass. Those people who didn't pass or who just barely passed would then receive the proper signal that maybe this major is not for them and so they would switch to something else. But their academic record would not be marred. </p>
<p>Another large aspect of the gap is those people who go to good schools, but not necessarily the very best ones (i.e. MIT, Stanford, Caltech, etc.), and don't do well at those schools. Like I said, anybody who graduates from the top schools like MIT or Stanford, even if they barely graduated, is going to have little difficulty in finding a job. It may not be the best job, but they can find a job. But that's not true of some of the schools that make up the next tier, like Cornell or Michigan, Wisconsin, Georgia Tech, Illinois, UCLA, and places like that. Perhaps even Berkeley. If you are going to a school like that and just barely making it (i.e. getting a 2.5 or less), you would have probably been better off majoring in something else, or going to a different school, or both. And certainly if you are flunking out of those schools, you clearly would have been better off going elsewhere. I know a guy who came in as a Chancellor's Scholar at Berkeley in EECS - and then proceeded to flunk out. He freely admits (and I agree) that he would have been far better off if he had gone to, say, UCDavis, or even a CalState. It's far better to graduate from San Jose State than to flunk out of Berkeley</p>