— Fighting over money and family assets has ruined many marriages, and a new study offers one insight into why finances can be such a contentious issue. When they look at the same data, many husbands and wives disagree significantly over the extent of the family's income, wealth and debts.

Husbands typically think the family income and wealth are greater than their wives think they are. And wives think the family debt is greater than their husbands think it is.

And both husbands and wives tend to think their spouses earn less than they say they do.

The bottom line, according to Ohio State University research scientist Jay Zagorsky, is many husbands and wives see their personal financial world quite differently. Zagorsky is an economist in the university's Center for Human Resource Research, and thus has access to a remarkable study of 33,000 persons covering a period of almost 40 years.

Revamped Resource

The National Longitudinal Surveys, funded primarily by the U.S. Bureau of Labor, began in the 1960s when researchers started fanning out across the country to ask willing participants all sorts of personal questions about everything from finances to health. In most cases, husbands and wives were interviewed separately. The participants were followed over the years, and they were asked questions that evolved as the participants themselves aged, resulting literally in a warehouse full of data.

Over the years researchers have tapped into that treasure trove and pulled out nuggets about how people generally adapt to a changing world, but until recently it was really difficult to fine-tune the data to the point of addressing specific, narrow questions.

But today the nine-track computer tapes that required a team of researchers, and a generous government grant, to pull out pertinent information are history. Zagorsky says a beefed-up personal computer allowed him to do in a few hours what would have taken months just a few years ago. The study was published in the May issue of The Journal of Socio-Economics.

As a researcher who thinks a lot about "why some people are rich and why some people are poor," as he puts it, Zagorsky's project began with a disagreement he was having with his own wife. Like most couples, they don't always see eye to eye, even on family finances.

So he set out to see if other couples share that problem. And the answer is a resounding yes.

More Money = Less Fights

The study focused on 1,195 couples who answered questions over many years concerning family finances. They were asked about income, and debt, and wealth, like equity in the family home.

About a third of the couples were in close agreement, Zagorsky says. Another third were pretty close, but "a third of the couples were wildly off," he says.

Income was adjusted for inflation to 1998 dollars, and the typical family earned $40,000, he says. Half of all the couples differed by $5,000 or more, and 25 percent differed by more than $10,000. And 10 percent of the couples differed by $15,000 or more, which percentage-wise, based on $40,000 income, is a whopping difference, Zagorsky says.

The difference is significant, he adds, since the study also shows that couples quarrel more over money than any other single problem, at least most of the time.

Questions about disagreements were asked during surveys conducted in only four years, 1988, 1992, 1994 and 1996. Interestingly, fights over money have declined over that period, from 1988, when 17 percent of the couples said they often argued about money, to less than 10 percent in 1996.

"That's really cool," Zagorsky says, because it shows that as personal income grows, couples are less inclined to fight over money.

"If you're just getting by, there's going to be a lot of fights over even small differences," he says. "But if you're making $90,000 and your bills are only $80,000, even if you don't agree, who cares?"

Angry, But on the Same Page

Yet some couples still fight about it, regardless of income. And that brings us to the Big Picture question. Why?

"I don't know," Zagorsky says.

He's an economist, after all, not a wizard.

But his data does tend to eliminate some of the more obvious explanations.

Like maybe husbands are braggadocios, liars who exaggerate their income to inflate their macho egos.

But at the end of each interview, researchers were asked if they thought the respondents were lying. So Zagorsky went back through the data and pulled out all the couples where the interviewer thought someone was lying.

He found that if he dropped the liars from the study, "the differences [among the remaining couples] actually got bigger, not smaller. So lying really wasn't causing it."

Maybe husbands just keep their wives in the dark when it comes to finances, so she really doesn't know how much the old boy makes, and how much debt they have. But it turns out that among most of the couples studied, the wives were handling the family paperwork, not the husbands, so they probably knew what was going on.

Since wives tend to be the bill-payers, however, that might explain at least one part of the conflict.

"They are probably much more focused on the debt of the family," Zagorsky says, and thus more likely to come up with a higher figure there.

Hot Potato Issues

So who's right in all these disputes? Who really knows the right figures, the husbands, or the wives?

We'll never know. No audits were performed on the couples' financial records, so it's impossible to tell if husbands and wives really exaggerate their own income, and deflate their spouses'.

But at least the study confirms what many couples already know. A lot of folks fight over money, and that can destroy a marriage in a hurry. The study shows that couples fought a lot less about religion, alcohol, and other women, than they did over money.

In fact, the only years that money failed to lead the list of disagreements were 1994 and 1996. In both those years, the top dog was chores.

Once they made more money, some folks seemed to have a problem in redistributing the workload. Like the old saying goes, there's no such thing as a free lunch.

Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.