Publications

This paper examines the extent to which agglomeration of the hospital service industry enhances the productivity of producing health care. Specifically, we use a large set of private insurance claims from the FAIR Health database to show that an increasing spatial concentration of hospital services results in a decreased cost of obtaining intermediate medical services. We explicitly test whether the reduced cost at concentrated locations arises from the ability to share intermediate service providers. The identification relies on state variation in medical lab technician licensure requirements, which influence the cost of intermediate services only through the cost of running a lab. Our findings suggest that agglomeration of the hospital service industry attracts specialized medical labs, which in turn help to reduce the cost of producing laboratory tests.

This paper exploits the homogeneity feature of the Singapore private residential condominium market and constructs matched home purchase price and rental price series using the repeated sales method. These matched series allow us to conduct time series analysis to examine the long-term present value relationship in the housing market. Three key findings are obtained. First, we fail to establish a cointegrating relationship between the home purchase price and rental price based on nationally estimated indexes. Second, area-specific indexes demonstrate strong cross-correlations, invalidating the use of first generation panel unit root tests that ignore these cross-correlations. Third, Pesaran's CIPS test indicates that the unit root hypothesis is rejected for the first difference of both indexes. We also do not reject the hypothesis that area-specific home purchases and rental price indexes are cointegrated with a cointegrating vector (1, - 1).

This paper examines two factors that help to explain geographic variation in health outcomes. The first factor concerns proximity to medical services. The second factor is state-specific health care policy that may impede access to nearby medical services. Four key findings are obtained. First, the effect of local doctors on reducing mortality rates of various diseases in a county attenuates with distance. Second, at approximately the same distance, in-state doctors contribute more to lowering mortality rates in the primary county than do out-of-state doctors. Third, the lesser impact of nearby out-of-state doctors is further reduced when the primary state adopts more stringent policies that restrict entry of out-of-state physicians. Fourth, the impact of nearby doctors is found to be stronger in more urbanized areas. This is consistent with agglomeration economies being effective in contributing, at least in part, to the productivity of treating patients.

Holly, Pesaran, and Yamagata (Journal of Econometrics 2010; 158: 160–173) use a panel of 49 states over the period 1975–2003 to show that state-level real housing prices are driven by economic fundamentals, such as real per capita disposable income, as well as by common shocks, such as changes in interest rates, oil prices and technological change. They apply the common correlated effects estimator of Pesaran (Econometrica 2006; 74(4): 967–101), which takes into account spatial interactions that reflect both geographical proximity and unobserved common factors. This paper replicates their results using a panel of 381 metropolitan statistical areas observed over the period 1975–2011. Our replication shows that their results are fairly robust to the more geographically refined cross-section units, and to the updated period of study.

This paper addresses two related questions that help to explain geographic variation in access to medical services. The first question examines the existence of agglomeration economies in the hospital service industry. The second considers whether the sharing of intermediate inputs contributes to spillovers from spatial concentration of hospital services. These questions are addressed by estimating a bivariate probit model that explicitly controls for potential correlations between whether a service is provided and how the service is provided. Three key findings are obtained. First, hospitals in more concentrated areas are more likely to outsource intermediate services to specialized intermediate service suppliers. This suggests that agglomeration economies exist in the hospital service industry and are generated in part through the sharing of intermediate inputs. Second, the presence of nearby small hospitals increases the tendency to outsource, which is consistent with a “Chinitz” effect identified elsewhere in the literature. Third, the agglomeration effect attenuates geographically.

The temporal variability of the canopy‐level urban heat island (UHI) of Singapore is examined for different temporal scales on the basis of observations during a 1‐year period. Temperature data obtained from different urban areas (commercial, Central Business District (CBD), high‐rise and low‐rise housing) are compared with ‘rural’ reference data and analysed with respect to meteorological variables and differences in land use. The results indicate that the peak UHI magnitude occurs 3–4 h (>6 h) after sunset in the commercial area, (at other urban sites). Higher UHI intensities generally occur during the southwest monsoon period of May–August, with a maximum of ∼7 °C observed in the commercial area under ideal meteorological conditions. Variations in seasonal precipitation explain some of the differences in urban–rural cooling. No clear relationship between urban geometry and UHI intensity can be seen, and intra‐urban variations of temperature are also shown to be influenced by other site factors, e.g. the extent of green space and anthropogenic heat. Lastly, results from the present study are compared with UHI data from other tropical and mid‐latitude cities.