Spatio-Temporal Sensitivity of Healthcare Accessibility: Insights from a System Dynamics Model

Recent research has increasingly focused on modeling the spatiotemporal dynamics of healthcare accessibility. However, a critical gap remains in understanding the relative influence of underlying factors, such as travel propensity, service availability, and population demand, and particularly how their influence varies across space and time. To address this gap, we proposed an analytic protocol that systematically evaluates these factors through four tiers: general, spatial, temporal, and spatio-temporal global sensitivity analysis (GSA). We demonstrated this framework's utility through a real-world case study in Florida, USA, integrated with a recently developed system dynamics model. The results revealed that disease rate had the greatest overall influence on variations in health accessibility. The spatial GSA showed clear heterogeneity in factor importance: travel propensity plays a more significant role in rural areas, whereas facility discharge rates have greater influence in urban settings. Furthermore, spatiotemporal GSA indicated that the influence of each factor varied substantially by both week and ZIP code. By quantifying factor influence across multiple scales, this framework offers evidence-based guidance for designing interventions tailored to different planning horizons and geographic contexts-such as short-term versus long-term, and local versus statewide strategies.