International Journal of Environmental Research and Public Health Article The Impact of a City-Level Minimum-Wage Policy on Supermarket Food Prices in Seattle-King County Jennifer J. Otten 1,* ID , James Buszkiewicz 2 ID , Wesley Tang 2, Anju Aggarwal 2, Mark Long 3 ID , Jacob Vigdor 3 and Adam Drewnowski 2 1 Environmental and Occupational Health Sciences, Center for Public Health Nutrition, University of Washington, Seattle 98195, WA, USA 2 Epidemiology, Center for Public Health Nutrition, University of Washington, Seattle 98195, WA, USA;
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[email protected] (A.D.) 3 Daniel J. Evans School of Public Policy and Governance, University of Washington, Seattle 98195, WA, USA;
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[email protected] (J.V.) * Correspondence:
[email protected] Received: 28 June 2017; Accepted: 6 September 2017; Published: 9 September 2017 Abstract: Background: Many states and localities throughout the U.S. have adopted higher minimum wages. Higher labor costs among low-wage food system workers could result in higher food prices. Methods: Using a market basket of 106 foods, food prices were collected at affected chain supermarket stores in Seattle and same-chain unaffected stores in King County (n = 12 total, six per location). Prices were collected at 1 month pre- (March 2015) and 1-month post-policy enactment (May 2015), then again 1-year post-policy enactment (May 2016). Unpaired t-tests were used to detect price differences by location at fixed time while paired t-tests were used to detect price difference across time with fixed store chain.