Retention, Learning by Doing, and Performance in Emergency Medical Services

To examine the strength of the volume-outcome relationship among paramedics, a group of providers that has not been previously studied in this context. By identifying the effects of individual learning on performance, we also assess the value of paramedics' retention. The prehospital emergency medical services (EMS) setting allows us to interpret any volume-outcome relationship as learning by doing, uncontaminated by reputation-based referrals because ambulance units are dispatched based on proximity. Incident-level EMS data spanning 1991 to 2005 from the Mississippi Emergency Medical Services Information System collected by the Mississippi Department of Health. Using linear and quantile methods with and without provider fixed effects, we estimate the relationship between experience accumulation and performance using the universe of trauma incidents involving injured patients (including motor vehicle crashes, falls, stabbings, and shootings). We find that greater individual volume is robustly related to improved performance. In addition, we find that the benefit of learning operates through both recent and past experiences, accrues differentially across tenure groups, and operates on both mean performance and the upper quantiles of the performance distribution. Persistent past and current volume effects suggest that policy and managerial implications in EMS should be directed at retention efforts to take advantage of individual learning by paramedics.