Progress in narrowing the gender pay gap nationally has slowed since 2001, according to The Simple Truth About the Gender Pay Gap, a report published on Thursday by the American Association of University Women. If that rate of change persists, U.S. women will be paid the same as men by 2152, according to the advocacy group’s report.1

At the same time, however, the ratio of male-to-female earnings nationally last year was 79.6 percent, the narrowest in inflation-adjusted data going back to 1960. And the outlook for parity can differ dramatically by state.

There’s a lot of debate about how to interpret a gender pay gap. Those who use the oft-cited statistic about American women making 78 cents to a man’s dollar as evidence of discrimination (the number is more like 80 cents) are not comparing apples to apples, some researchers argue, citing different hours worked and divergent career choices, among other things.

Skepticism of this measurement is valid, said Catherine Hill, the AAUW’s vice president of research. It’s an overarching number that mixes together a lot of things, including age and occupation. She said that figure is more notable for showing trends, such as a narrowing of the gap during the 1980s and 1990s, “when women’s educational achievements were a driving force,” and a flattening of that line tracking the gap over the past 15 years.

After factoring in age, occupation, and other data, there’s still a gender pay gap that can’t be explained away, said Harvard economics professor Claudia Goldin. “But,” she adds, “we aren’t smart enough to say that a gender pay gap is due to discrimination.”

The AAUW’s Hill said that, after controlling for 11 factors, the report found a 7 percent gap exists one year after women graduate from college. “That tells us something else is going on,” she said. “Yes, the choices we make are a big part of it, but it’s also the choices people assume we’re going to make,” such as taking time out of the workforce to raise kids or to take care of other family members.