Measuring inequality in physician distributions using spatially adjusted Gini coefficients

Abstract

Objective: To measure inequality in physician distributions using Gini coefficient and spatially adjusted Gini coefficients.

Design: Measurements were based on the distribution of physician data from the Taiwan National Health Insurance Research Database (NHIRD) and population data from the Ministry of the Interior in Taiwan.

Settings: The distribution of population and physicians in Taiwan from 2001 to 2010.

Participants: This study considered 35 000 physicians who are registered in Taiwan.

Main outcome measures: To calculate the Gini coefficient and spatially adjusted Gini coefficients in Taiwan from 2001 to 2010.

Results: The Gini coefficient for each year, from 2001 to 2010, ranged from 0.5128 to 0.4692, while the spatially adjusted Gini coefficients based on travel time and travel distance ranged, respectively, from 0.4324 to 0.4066 and from 0.4408 to 0.4178. We found that, in each year, irrespective of the type of spatial adjustment, the spatially adjusted Gini coefficient was smaller than the Gini coefficient itself. Our empirical findings support that the Gini coefficient may overestimate the maldistribution of physicians.

Conclusions: Our simulations demonstrate that increasing the number of physicians in medium-sized cities (such as capitals of counties or provinces), and/or improving the transportation time between medium-sized cities and rural areas, could be feasible solutions to mitigate the problem of geographical maldistribution of physicians.

Keywords: Gini coefficient; geographic correlation; physician inequality; spatial statistics.