It was a jaw-dropping statistic, widely influential in the movement to change America's divorce and child-support laws.

Eleven years ago, sociologist Lenore Weitzman published ''The Divorce Revolution,'' her groundbreaking study of California's no-fault divorce system. In it, she reported that women's households suffered a 73 percent drop in their standard of living in the first year after divorce, while men's households enjoyed a 42 percent rise.

Since then, the figures have been quoted hundreds of times in newspapers, politicians' speeches and court rulings.

Richard Peterson, a New York sociologist who reanalyzed Weitzman's data from computer and paper records archived at Radcliffe College's Murray Research Center, found a 27 percent decline in women's post-divorce standard of living and a 10 percent increase in men's - still a serious gap, but not the catastrophic one that Weitzman saw.

Weitzman, a professor of sociology and law at George Mason University in Fairfax, Va., now acknowledges her figures were wrong. She blames the loss of her original computer data file, a weighting error or a mistake in the computer calculations performed by a Stanford University research assistant.

Peterson checked Weitzman's conclusions because they were so much at odds with what other researchers had found and because they conflicted with some of her own data. For several years after the publication of her book, she did not make her data available to other researchers; she explained there were errors in the master computer data file that she wanted to correct first.

Peterson's research and Weitzman's response will be published in the American Sociological Review next month.

The publicity that greeted Weitzman's findings was similar to what occurred after a 1986 study said that if a col lege-educated white woman hasn't married by age 40, she has only a 1-in-100 chance of getting hitched. That figure was later discredited, but not before a Newsweek cover story declared that a 40-year-old woman had a better chance of being killed by a terrorist than of getting married.

The dispute over Weitzman's standard-of-living figures is more than just academic.

A search of the Nexis database found more than 175 newspaper and magazine stories citing Weitzman's numbers. Peterson said he also found citations in 348 social-science articles, 250 law-review articles and 24 appeals and Supreme Court cases. The statistic even appeared in President Clinton's 1996 budget.

''This has been one of the most widely quoted statistics in recent history,'' said Anne Colby, director of the Murray Center.

Weitzman's figures have been cited by policy-makers and others as hard evidence of what's become known as the ''feminization of poverty.'' Her book is credited with helping bring about stricter child-sup port enforcement and more flexible property-division laws around the country.

Moreover, in a recent essay, Susan Faludi, feminist author of ''Backlash,'' called Weitzman's statistic ''the centerpiece for recent attacks on no-fault divorce.''

Weitzman's study, which looked at divorcing families in Los Angeles in 1977 and 1978, was designed to evaluate California's first-in-the-nation no-fault divorce law and accompanying economic reforms.

Because Weitzman's findings varied so dramatically from what other researchers had found, many analysts concluded the bigger gap in California was caused by the state's switch to no-fault divorce.

In the past year, several states, including Michigan and Iowa, have considered a return to fault-based divorce, in which one spouse must assert adultery, cruelty or some other type of wrongdoing.

But Weitzman, her critics and other divorce scholars say no-fault divorce is not to blame for some women's economic plight. Peterson says research on both fault and no-fault systems has found similar gaps - about a 30 percent drop in women's standard of living and a 10 percent rise in men's.

Weitzman says it was the accompanying economic changes - originally intended to foster greater equality - that hurt women and children.

Those changes included requiring equal division of the marital property instead of giving judges discretion, and basing alimony and child support strictly on need and ability to pay instead of fault.

''Judges were giving women equality with a vengeance, telling them they were equally responsible for their support . . . at a time when they still had responsibility for children and didn't have the work experience of their former husbands,'' she said.

Also, judges often required the immediate sale of the family home so assets could be split equally between husband and wife. That meant the children were uprooted and forced to move to a new house and sometimes a new school, Weitzman said.

Her book helped bring about changes in California and elsewhere, including better child-support enforcement and laws allowing judges to delay the sale of the family home until the children are grown, she said.