Application of Decomposition Analysis of Spatial Accessibility (DASA) in Health Services Research

Withdrawal mapping is effective in showing the educational impact of residency programs and medical schools. It is often used for advocacy and education purposes, but it lacks grounding in the theoretical foundation of spatial accessibility research. This study proposes an improved technique called Decomposition Analysis of Spatial Accessibility, or DASA, to decompose spatial accessibility by applying the withdrawal mapping concept to the classical 2SFCA application. This study applies the DASA technique to three case studies with policy implications. The first case study details the contribution of Black surgeons to public access to the surgical workforce. The second case study details the contribution of international medical graduates from the original seven travel-ban countries. The third case study demonstrates the market competition between family physicians and general pediatricians. The study showcases the usefulness (particularly for workforce-planning for underserved populations) of the DASA technique in understanding subgroup contributions in spatial accessibility analyses.