Emergency medical services (EMS) systems vary across country, state, and even county lines. Which model provides the most effective and safe care has been hotly debated. Some models employ a fire-based EMS response, whereas others are privately funded and are completely separate from other public responders. Response can be uniform or tiered, which means that either ALS units respond to every call or calls are triaged based on their severity and units are dispatched accordingly. This requires a sophisticated dispatch algorithm that screens for emergencies of highest priority. Persse et al. sought to determine the difference in survival in out-of-hospital ventricular fibrillation arrest between a tiered response EMS model and an all advanced life support (ALS) response model within the same system.