Who's winning, labor or capital?

The question may seem like a no-brainer. Barroom analysts and fans of Lou Dobbs may find it self-evident that the ordinary working person's slice of the economic cake has been getting smaller and crumbier.

Let's recite the evidence together: Sluggish wage growth. Frozen pensions. Higher health-care co-pays. Shrinking job security. All set against the continued rocket-boom of executive compensation, Wall Street bonuses, and record corporate profits.

But headlines and anecdotes aren't data, as economists never tire of pointing out. If you want to prove the tide is rising for the owners of capital while the rest of us flounder or drown, you've got to crunch some numbers.

Fortunately, it turns out that how the economic pie is split isn't just a hot topic in boardrooms and union halls. Economists are grappling with the issue as well - and may be just as divided in their conclusions.

For example, Morgan Stanley chief economist Stephen Roach recently warned of a dangerous tilt developing in the world's industrialized economies.

Capital is claiming a disproportionate share of national income in the United States, Europe and Japan, he said. In other words, corporate profits, investment gains, and other forms of nonlabor income are all growing faster than the wages and benefits received by workers.

But is this a long-term trend - with dangerous implications for economic growth and political stability in the future? Or is it just part of a cycle - a tide that ebbs and flows, a pendulum that reverses course every few years?

That's not as clear.

Deutsche Bank AG economist Joshua Feinman laid out the evidence recently, citing government statistics from the last decade.

In mid-2001, he said, labor's share of U.S. national income - including wages, benefits, commissions and bonuses - was 66.8 percent.

By the middle of 2006, that share had shrunk to 63.8 percent.

Over the same period, capital's share - including profits, interest, rents, and so-called proprietors' income - went from 25.1 percent to 27.6 percent.

(The shares don't equal 100 percent because of a third, "other" category.)

So it's true: Capital's share is growing at labor's expense - at least for now.

Look back a few more years, however, and the picture changes.

In mid-1997, labor's share of the national income pie was 63.7 percent - about the same as the latest number.

Capital's share in 1997 was 27.5 percent - also near its most recent level.

It turns out, moreover, that, for at least 50 years, capital and labor have each maintained more or less the same shares of the economic pie.

As a rough rule of thumb, about two-thirds of all the income generated in the national economy is paid to workers, one way or another.

Owners of capital - including stockholders, lenders, landlords and proprietors - receive close to one-third.

Those proportions fluctuate over time, which isn't too surprising: Stock market booms can push up capital income, while a tight job market can tilt the field toward labor.

Shifts in the two sides' shares don't happen with perfect regularity, but the changes aren't random, either. A rise in capital income attracts more investment, which creates jobs (and more income for labor) while squeezing profits. And so on.

But some analysts say it's different this time.

Globalization has introduced a vast new labor supply into the equation, putting unprecedented pressure on wages in the United States and other developed economies. Capital is reaping the benefits, while workers get squeezed.

Are they right? Deutsche Bank's Feinman says it's too soon to tell.

"It's not an open-and-shut case," he told me. "At this stage, it's premature to argue that this is other than a normal cyclical variation" in the shares of labor and capital.

It would be tempting to jump to a conclusion on this issue. But given how much is at stake, the right answer could be well worth the wait.