February 1, 2021

A Difference-in-Difference Study Evaluating the Effect of Minimum Wage Policy on Body Mass Index and Related Health Behaviors

By Caitlin Caspi, Molly De Marco, Thomas Durfee, Abayomi Oyengua, Leah Chapman,Julian Wolfson, Samuel Myers, Jr., Lisa Harnack


Minimum wage laws are a promising policy lever to promote health equity, but few rigorous evaluations have tested whether and how minimum wage policy affects health outcomes. This paper describes an ongoing difference-in-difference study evaluating the health effects of the 2017 Minneapolis Minimum Wage Ordinance, which incrementally increases the min- imum wage to $15/hr. We present: (1) the conceptual model guiding the study including mediating mechanisms, (2) the study design, (3) baseline findings from the study, and (4) the analytic plan for the remainder of the study. This prospective study follows a cohort of 974 low-wage workers over four years to compare outcomes among low-wage workers in Minneapolis, Minnesota, and those in a comparison city (Raleigh, North Carolina). Measures include height/weight, employment paystubs, two weeks of food purchase receipts, and a survey capturing data on participant demographics, health behaviors, and household finances. Baseline findings offer a profile of individuals likely to be affected by minimum wage laws. While the study is ongoing, the movement to increase local and state minimum wage is currently high on the policy agenda; evidence is needed to determine what role, if any, such policies play in improving the health of those affected.

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