RT Journal Article SR Electronic T1 Public Insurance Expansions and Labor Demand in Physician Practices JF Journal of Human Resources JO J Hum Resour FD University of Wisconsin Press SP 0920-11176R2 DO 10.3368/jhr.0920-11176R2 A1 Hilary Barnes A1 Alice J. Chen A1 Matthew D. McHugh A1 Michael R. Richards YR 2023 UL http://jhr.uwpress.org/content/early/2023/05/01/jhr.0920-11176R2.abstract AB Existing research has examined the demand-side effects of ACA Medicaid expansions, but supply-side implications are not well-understood. Using a model of uncertain demand, we show how firms choose between fixed- and variable-cost labor investments. We empirically test the model predictions via a difference-in-differences strategy that uses Medicaid expansions and detailed staffing information on over 129,000 physician practices. We find no substitution toward less expensive provider types whose employment carries fixed costs in the short run; instead, practices are 4-8 percent less likely to employ any nurse practitioner or physician assistant post-expansion. Small practices seem to drive the restrained labor demand effects.