Nonlinear relationship between health care expenditure and its determinants: a panel smooth transition regression model

This paper employs a panel of 16 OECD countries over the period 1975–2009 to reexamine the health care expenditure (HCE)-income relationship by considering a lagged ratio of public expenditures on health as the transition variable in panel smooth transition regression (PSTR) models. PSTR models can capture the heterogeneity of any individual country, provide more detailed information for policy makers of an individual government, and resolve the insufficient observations problem that frequently appears in annual country-level data. Our empirical results indicate that the relationship between HCE and its determinants, including income, time (trend), and age structure variables, is nonlinear and varies with time and across countries. The time (trend) variable—a proxy for technical progress in health care—has a non-linear impact on HCE. Ignoring the variables—technological change of health care and age structure of population—will result in over-estimates of the income elasticities of HCE. Moreover, HCE behaves as a necessity good, and the income elasticity increases when the five-period lagged ratio of public expenditures on health increases. Clearly, the ratio of government financing on health plays an important role in influencing HCE.