Seattle’s minimum wage increases did not boost supermarket prices in the city in the two years after the policy began, according to a study led by researchers at the University of Washington School of Public Health.

In the paper, published in the International Journal of Environmental Research and Public Health, researchers examined the effect of Seattle’s minimum wage ordinance on local area supermarket food prices over time and as wages phased in to $15 per hour.

Overall, the authors found no significant evidence of price increases associated with the minimum wage ordinance. The paper also sought to evaluate the potential for differential price changes that might be related to diet quality, including analyses by food group, level of food processing and nutrient quality. The authors found no evidence of significant price increases in any of the diet quality measures examined that could be attributed to the minimum wage ordinance.

“This is really great news for low-wage earning Seattle shoppers,” said lead author James Buszkiewicz, a doctoral candidate in the Department of Epidemiology at the UW School of Public Health. “Typically null findings do not get that much attention, but in this case, if local food prices remain steady while earnings increase for low and minimum wage workers, then that could mean increased purchasing power for things like fresh fruit and vegetables for the consumers that need it most.”

Buszkiewicz said that the study findings may not be generalizable to all cities and states experiencing minimum wage increases given Seattle’s unique economic circumstances. However, he hopes that this study will serve as a model for other investigators to examine potential price hikes in their state or area.

The investigators collected prices for 106 food items from six large supermarket chain stores affected by the ordinance in Seattle and in six of the same-chain stores in King County and unaffected by the ordinance. The price check occurred at four time points: one month pre- (March 2015), one month post- (May 2015), one year post- (May 2016), and two years post- (May 2017) ordinance implementation.

Funding for the food prices study came from Arnold Ventures and the City of Seattle. Other co-authors for the food prices study include Anju Aggarwal and Adam Drewnowski of the UW School of Public Health; Mark Long from the Evans School of Public Policy and Governance; and Catherine House, who was a graduate student in the UW Nutritional Sciences Program.

(This story was originally published by UW News.)