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.