Why haven’t you gotten a raise?

In the past few years, corporate profits have climbed ever higher. Legions of unemployed people are now finding gainful employment, with joblessness finally falling below 6 percent. Meanwhile, if you’re anything like the average American worker, your pay has been flat, just barely keeping pace with inflation. If you’re in the very middle of America’s income distribution, in fact, your overall household income is lower today than it was when the recession officially ended more than five years ago.

This is all a bit of a puzzle.

Usually unemployment declines go hand in hand with raises, after a slight lag. As the pool of idle workers shrinks, employers must offer higher pay to attract, and retain, labor. This time they are not, even though employers are increasingly complaining about the kinds of talent shortages that usually lead to upward wage pressures: Nearly half of the firms that filled or attempted to fill job openings in the past three months said there were “few” or “no” qualified applicants available, according to a National Federation of Independent Business survey.

There are a few possible explanations behind the missing wage growth.

One has to do with the mix of jobs being created. Some research has shown that jobs lost during the recession were disproportionately in high- and mid-wage industries (e.g., construction), while those gained in the recovery have been concentrated in low-wage industries (e.g., retail). Perhaps wage stagnation is just an illusion, created by this shift. The Labor Department’s Employment Cost Index, however, strips out the influences of changing industry and occupational composition and still shows relatively flat wages.

Another potential culprit involves runaway health-care costs, which might eat into other categories of employee compensation, including wages. But growth in benefit costs (including health insurance) has slowed dramatically in the past few years, and as a result workers’ total compensation has also remained pretty flat.

Then there’s the Spoiled Boss hypothesis.

For years jobless workers were desperate to find something, anything, to pay the bills, and they lowered their demands for what that something-or­anything job should disburse. Perhaps bosses got spoiled, expecting bargain-basement deals on wages to continue indefinitely, and have been reluctant to offer higher pay even when they can’t find qualified job applicants. This attitude doesn’t seem sustainable, though, unless a lot of companies made irreversible capital investments predicated on permanently low wages (e.g., buying manned checkout counters rather than self-checkout machines).

Maybe it’s not bosses but frightened employees who are really to blame. The main avenue through which workers get raises is job-hopping; right now, though, the share of workers voluntarily quitting their jobs remains depressed, even though job vacancies are back to pre­recession levels. Maybe risk-averse, grateful-to-just-be-employed workers have stopped looking for competing job offers, and the resulting decline in “churn” is weighing on their paychecks.

I suspect the main reason that wages haven’t risen, though, is that the job market is not nearly as “tight” as the headline unemployment rate makes it appear.

Nine million workers are currently counted as unemployed. But another 6 million are sitting on the sidelines, wanting to work yet not officially tallied among the unemployed because they’re not actively applying for jobs. Labor-force participation rates remain shockingly low, even among Americans in their prime working-age years. This shadow surplus of workers takes the pressure off employers to raise wages, whatever their protestations about labor shortages.

The most optimistic explanation suggests that Americans might be on the verge of getting a long-awaited raise after all.

As Federal Reserve Chair Janet Yellen discussed at a conference in August, the “pent-up wage deflation” theory says stagnant wages today are payback for too-high wages during the “Great Recession.” The basic logic is this: Concerns about employee morale kept bosses from cutting nominal pay during the downturn, and then super-low levels of inflation didn’t erode the value of their wages much either. With workers already seemingly overpaid, employers felt no need to raise wages when the recovery began. But once this “pent-up wage deflation” works its way through the system, and the country nears full employment, wages should shoot up again.

Whether Americans are aware of this technical theory or not, they’re now predicting the same result: The share of businesses saying they expect to increase compensation in the coming months is finally creeping up, and more consumers are expecting income gains in the year ahead than at any time since Lehman imploded in 2008. For the sake of the economy, public coffers and your pocketbook, let’s hope they’re right.