When Seattle officials voted three years ago to incrementally boost the city’s minimum wage up to $15 an hour, they’d hoped to improve the lives of low-income workers. Yet according to a major new study that could force economists to reassess past research on the issue, the hike has had the opposite effect.

The city is gradually increasing the hourly minimum to $15 over several years. Already, though, some employers have not been able to afford the increased minimums. They’ve cut their payrolls, putting off new hiring, reducing hours or letting their workers go, the study found.

A waitress at a Seattle restaurant carries food to a table in 2014. A new study finds that low-wage workers may not benefit overall from an increase in the minimum wage, but the study does not include larger employers. Associated Press/Ted S. Warren Related Headlines LePage signs tip credit restoration bill

The costs to low-wage workers in Seattle outweighed the benefits by a ratio of three to one, according to the study, conducted by a group of economists at the University of Washington who were commissioned by the city. The study, published as a working paper Monday by the National Bureau of Economic Research, has not yet been peer reviewed.

On the whole, the study estimates, the average low-wage worker in the city lost $125 a month because of the hike in the minimum.

The paper’s conclusions contradict years of research on the minimum wage. Many past studies, by contrast, have found that the benefits of increases for low-wage workers exceed the costs in terms of reduced employment – often by a factor of four or five to one.

“This strikes me as a study that is likely to influence people,” said David Autor, an economist at the Massachusetts Institute of Technology who was not involved in the research. He called the work “very credible” and “sufficiently compelling in its design and statistical power that it can change minds.”

Yet the study will not put an end to the dispute. Experts cautioned that the effects of the minimum wage may vary according to the industries dominant in the cities where they are implemented along with overall economic conditions in the country as a whole.

Critics of the research pointed out what they saw as serious shortcomings. In particular, to avoid confusing establishments that were subject to the minimum with those that were not, the authors did not include large employers with locations both inside and outside of Seattle in their calculations.

“Like, whoa, what? Where did you get this?” asked Ben Zipperer, an economist at the left-leaning Economic Policy Institute in Washington.

“My view of the research is that it seems to work,” he said. “The minimum wage in general seems to do exactly what it’s intended to do, and that’s to raise wages for low-wage workers, with little negative consequence in terms of job loss.”

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