Recent research by two University of Chicago economists studied 417 newspapers – 70 percent of total newspaper circulation in the U.S. – for bias and found that newspapers are more likely than not to reflect their readers' views and political leanings.

In conducting their study, entitled “What Drives Media Slant? Evidence From U.S. Daily Newspapers,” Matthew Gentzkow and Jesse M. Shapiro parsed the words of politicians — all the words — from the 2005 Congressional Record. They found the 1,000 most partisan phrases uttered in the year and measured this by comparing how frequently a phrase was used by one side or the other.

In 2005, phrases like “death tax,” “illegal aliens,” “Terri Schiavo,” and “nuclear power” came mostly from Republicans. Phrases like “minimum wage,” “public broadcasting,” “middle class” and “oil companies” came mostly from Democrats. Using these phrases, the two economists made a simple index of partisanship that comported nicely with standard measures like a politician’s score on the Americans for Democratic Action ideological scale.

The study then analyzed 417 U.S. newspapers as if they were politicians. The researchers measured, for example, all the times articles about Social Security referred to “personal accounts” (Republican) or “private accounts” (Democratic). Their measure of partisan slant came only from the news coverage. They did not include anything from editorial pages.

But more important, once the authors determined this measure, they showed that the main driver of any slant was the newspaper’s audience, not bias by ownership. The studied generally showed that if a paper was identified “liberal” or “conservative,” it tended to sell well in areas that reflected that particular political stance.

Their measure indicates that The Los Angeles Times, for example, is a liberal paper. Its circulation suffers in Southern California ZIP codes where donations to Republicans are especially high.

So in looking for a newspaper’s supposed slant, follow the money – in this case, the circulation money.