In this paper, we decompose provider practice style into two dimensions, whether providers are more or less aggressive in their use of invasive treatments (a mean effect) and whether there are differences in the extent to which providers tailor their treatment decisions to the characteristics of individual patients (a slope effect). We then ask whether these differences matter for costs and health outcomes. Specifically, we use a rich data set of Florida patients arriving at the Emergency Roo (ER) with acute myocardial infarction (AMI), i.e. heart attack, between 1992 and the second quarter of 2014. When such a patient arrives at the ER, the clinicians on duty must quickly decide on a course of action, so that there is less than usual scope for selecting a provider.1We focus on within hospital-year variation in provider behavior and the sample is limited to hospitals that have experience performing invasive cardiac procedures to ensure that there is in fact a viable choice to be made.