The Georgetown study estimates that nearly two-thirds of the STEM job openings in the United States, or about 180 000 jobs per year, will require bachelor's degrees. Now, if you apply the Commerce Department's definition of STEM to the NSF's annual count of science and engineering bachelor's degrees, that means about 252 000 STEM graduates emerged in 2009. So even if all the STEM openings were entry-level positions and even if only new STEM bachelor's holders could compete for them, that still leaves 70 000 graduates unable to get a job in their chosen field.

Of course, the pool of U.S. STEM workers is much bigger than that: It includes new STEM master's and Ph.D. graduates (in 2009, around 80 000 and 25 000, respectively), STEM associate degree graduates (about 40 000), H-1B visa holders (more than 50 000), other immigrants and visa holders with STEM degrees, technical certificate holders, and non-STEM degree recipients looking to find STEM-related work. And then there's the vast number of STEM degree holders who graduated in previous years or decades.

Even in the computer and IT industry, the sector that employs the most STEM workers and is expected to grow the most over the next 5 to 10 years, not everyone who wants a job can find one. A recent study by the Economic Policy Institute (EPI), a liberal-leaning think tank in Washington, D.C., found that more than a third of recent computer science graduates aren't working in their chosen major; of that group, almost a third say the reason is that there are no jobs available.

What's perhaps most perplexing about the claim of a STEM worker shortage is that many studies have directly contradicted it, including reports from Duke University, the Rochester Institute of Technology, the Alfred P. Sloan Foundation, and the Rand Corp. A 2004 Rand study, for example, stated that there was no evidence "that such shortages have existed at least since 1990, nor that they are on the horizon."

That report argued that the best indicator of a shortfall would be a widespread rise in salaries throughout the STEM community. But the price of labor has not risen, as you would expect it to do if STEM workers were scarce. In computing and IT, wages have generally been stagnant for the past decade, according to the EPI and other analyses. And over the past 30 years, according to the Georgetown report, engineers' and engineering technicians' wages have grown the least of all STEM wages and also more slowly than those in non-STEM fields; while STEM workers as a group have seen wages rise 33 percent and non-STEM workers' wages rose by 23 percent, engineering salaries grew by just 18 percent. The situation is even more grim for those who get a Ph.D. in science, math, or engineering. The Georgetown study states it succinctly: "At the highest levels of educational attainment, STEM wages are not competitive."

Given all of the above, it is difficult to make a case that there has been, is, or will soon be a STEM labor shortage. "If there was really a STEM labor market crisis, you'd be seeing very different behaviors from companies," notes Ron Hira, an associate professor of public policy at the Rochester Institute of Technology, in New York state. "You wouldn't see companies cutting their retirement contributions, or hiring new workers and giving them worse benefits packages. Instead you would see signing bonuses, you'd see wage increases. You would see these companies really training their incumbent workers."

"None of those things are observable," Hira says. "In fact, they're operating in the opposite way."

So why the persistent anxiety that a STEM crisis exists? Michael S. Teitelbaum ... has studied the phenomenon, and he says that in the United States the anxiety dates back to World War II. Ever since then it has tended to run in cycles that he calls "alarm, boom, and bust." He says the cycle usually starts when "someone or some group sounds the alarm that there is a critical crisis of insufficient numbers of scientists, engineers, and mathematicians" and as a result the country "is in jeopardy of either a national security risk or of falling behind economically."

"The government responds either with money [for research] or, more recently, with visas to increase the number of STEM workers," Teitelbaum says. "This continues for a number of years until the claims of a shortage turn out not to be true and a bust ensues." Students who graduate during the bust, he says, are shocked to discover that "they can't find jobs, or they find jobs but not stable ones."

Clearly, powerful forces must be at work to perpetuate the cycle. One is obvious: the bottom line. Companies would rather not pay STEM professionals high salaries with lavish benefits, offer them training on the job, or guarantee them decades of stable employment. So having an oversupply of workers, whether domestically educated or imported, is to their benefit. It gives employers a larger pool from which they can pick the "best and the brightest," and it helps keep wages in check. No less an authority than Alan Greenspan, former chairman of the Federal Reserve, said as much when in 2007 he advocated boosting the number of skilled immigrants entering the United States so as to "suppress" the wages of their U.S. counterparts, which he considered too high.

Governments also push the STEM myth because an abundance of scientists and engineers is widely viewed as an important engine for innovation and also for national defense. And the perception of a STEM crisis benefits higher education, says Ron Hira, because as "taxpayers subsidize more STEM education, that works in the interest of the universities" by allowing them to expand their enrollments.

(emphasis obviously mine)