The first study, led by Michael Reich and Sylvia Allegretto based at the University of California, Berkeley, concludes that the 2015 and 2016 increases to $11 and $13 an hour had the intended effects of raising incomes for low-wage workers without having discernible impact on the number of jobs. These findings are consistent with the bulk of economic studies of minimum wage increases over the past couple of decades.
In the second, a University of Washington team concluded that the 2016 wage increase reduced the number of low-wage jobs by 9% and actually lowered the incomes of low-wage workers. This diverges from the majority of economic research. Across the U.S., city, state, and federal governments have changed minimum wages dozens of times over the past two decades. Multiple economists from across the ideological spectrum have studied these changes, and even opponents of minimum wage increases have not found impacts anywhere near the scale of the UW team.
The UWs counter-intuitive findings underscore several methodological flaws:
They limit their study only to single-site establishments, because their data could not distinguish whether employees of multi-site chains think Molly Moons, Mud Bay, Mod Pizza, Starbucks actually worked inside or outside the city limits. That leaves 40% of workers excluded from their study. It also means that leaving a job at small business for a job at a larger company counts incorrectly as a job loss.
The UW team created a control by comparing Seattles employment statistics with other parts of the state. But there is no place in Washington that has a similar economy to Seattle. Seattle has an economy more like San Francisco or New York than Everett or Spokane. The Berkeley team used the more accepted methodology of generating a control from similar areas across the country, rather than just the state. Moreover, the Berkeley team compared numbers for the previous 5 years, while the UW only looked at the previous 9 months.
The UW study focused on jobs paying $19 an hour or less, making the assumption that fewer jobs in this bracket meant lost opportunity for workers who used to be in this pay range. But what were seeing in Seattle is that jobs that used to pay $18 an hour now pay $20 due to competition for employees. In the UW study, this was unaccounted for and incorrectly counted as job loss.