A Sequential Shrinkage Estimating Method for Tobit Regression Model

In the applications of Tobit regression models we always encounter the data sets which contain too many variables that only a few of them contribute to the model. Therefore, it will waste much more samples to estimate the “non-effective” variables in the inference. In this paper, we use a sequential procedure for constructing the fixed size confidence set for the “effective” parameters to the model by using an adaptive shrinkage estimate such that the “effective” coefficients can be efficiently identified with the minimum sample size based on Tobit regression model. Fixed design is considered for numerical simulation.

2013—2019年上海市市级医院运行效率及影响因素

目的分析2013—2019年上海市市级医院的运行效率及其影响因素,为医院提质增效提供依据。方法以上海市12家市级综合医院与18家市级专科医院为研究对象,运用DEA-BCC模型、Malmquist指数模型与Tobit回归模型测算样本医院的效率及其动态变化情况,并分析其影响因素。结果2013—2019年,样本综合医院的全要素生产率与技术进步指数增长,技术效率指数下降,样本专科医院的全要素生产率、技术进步指数、技术效率均增长。进一步分析发现,卫生技术人员占比、床位使用率、院区总数与技术效率正相关,31 d再入院率、药占比与技术效率负相关。结论样本医院运行效率较高,但多数医院处于规模不经济状态,应调整发展规模,优化资源配置。样本医院的全要素生产率提高主要依靠技术进步推动,建议加强人才建设,提高技术创新能力。样本医院运行效率受多重因素影响,制定战略目标时应结合实际情况进行统筹规划。

Traffic Incident Management Performance Measures: Ranking Agencies on Roadway Clearance Time

This study develops a procedure to rank agencies based on their incident responses using roadway clearance times for crashes. This analysis is not intended to grade agencies but to assist in identifying agencies requiring more training or resources for incident management. Previous NCHRP reports discussed usage of different factors including incident severity, roadway characteristics, number of lanes involved and time of incident separately for estimating the performance. However, it does not tell us how to incorporate all the factors at the same time. Thus, this study aims to account for multiple factors to ensure fair comparisons. This study used 149,174 crashes from Iowa that occurred from 2018 to 2021. A Tobit regression model was used to find the effect of different variables on roadway clearance time. Variables that cannot be controlled directly by agencies such as crash severity, roadway type, weather conditions, lighting conditions, etc., were included in the analysis as it helps to reduce bias in the ranking procedure. Then clearance time of each crash is normalized into a base condition using the regression coefficients. The normalization makes the process more efficient as the effect of uncontrollable factors has already been mitigated. Finally, the agencies were ranked by their average normalized roadway clearance time. This ranking process allows agencies to track their performance of previous crashes, can be used in identifying low performing agencies that could use additional resources and training, and can be used to identify high performing agencies to recognize for their efforts and performance.

Irrigation Water Use Efficiency of Farmers and Its Determinants: Evidence from a Survey in Northwestern China

Irrigation water shortage is becoming an increasingly serious problem in agricultural production. In this case, it is very important for policy makers to take measures to improve irrigation water use efficiency, especially in the water-scarce areas. In this paper, the data envelopment analysis （DEA） techniques, based on the concept of input-specific technical efficiency were used to develop farm-level technical efficiency measures and sub-vector efficiencies for irrigation water use. The Tobit regression technique was then adopted to identify the factors that influence irrigation water efficiency differentials under the shortage of water resources. Based on a sample data of 432 wheat farmers in northwestern China, our experimental results of the DEA analysis showed the average technical efficiency of 0.6151. It suggested that wheat farmers could increase their production by as much as 38.49% by using inputs more efficiently. Further, the mean irrigation water efficiency of 0.3065, suggested that wheat farmers could produce the same quantity of wheat using the same quantity of inputs but with 69.35% less water. The results of the Tobit regression analysis showed that the farmer＇s age, income, education level, and the farm size tended to affect the degree of irrigation water efficiency positively, and the channel conditions and different irrigation methods made a significant impact on irrigation water use efficiency. Furthermore, the arrangements of exclusive water property rights and competitive water price mechanism have effectively encouraged the water saving behavior of farmers. These results are valuable for policy makers since it could help to guide policies towards high irrigation water use efficiency.

Evaluation and Influence Factor of Green Efficiency of China’s Agricultural Innovation from the Perspective of Technical Transformation

Agricultural innovation is important for the green transformation of agriculture.Based on the perspective of technology transformation,this paper builds a theoretical analysis framework and evaluation index system for green efficiency of agricultural innovation,and discusses the evolution laws and influencing factors of the green efficiency of China’s agricultural innovation from 2005 to 2017 utilizing the DEA model,Malmquist index,and Tobit regression analysis.The results show that:1)The overall green efficiency of China’s agricultural innovation is not high,the green efficiency of agricultural innovation in eastern China is mainly driven by pure technical efficiency,while that in central and western China is mainly driven by the scale efficiency.The green efficiency of agricultural innovation shows significant spatial differences,and the low efficiency and relatively low-efficiency regions moved to central and southeastern China.2)Technical progress is the main force affecting the change of green total factor productivity of China’s agricultural innovation,seeing a trend of decrease followed by an increase.Pure technical efficiency and scale efficiency exhibit an increasing-decreasing trend,and gradually transform into key factors that restrict the improvement of the green total factor productivity of agricultural innovation.3)Agricultural technologies’diffusion,absorption,and implementation are three influencing factors of the green efficiency of agricultural innovation.The local level of informatization,the number of agricultural technicians in enterprises and institutions,average education level of residents,and the level of agricultural mechanization have positive impacts on the promotion of the green efficiency of agricultural innovation,promoting the diffusion,absorption and implementation of agricultural innovation technology can significantly improve the green efficiency of agricultural innovation.

Evaluating the environmental efficiency of the U.S.airline industry using a directional distance function DEA approach

This study applies a directional distance function(DDF)data envelopment analysis(DEA)model to measure the environmental efficiency of 12 U.S.airlines 2013–2016 by considering flight delay and greenhouse gas(GHG)emissions as joint undesirable outputs.First,the environmental efficiency of airlines is compared using the CCR DEA(without flight delay)and DDF DEA(with flight delay).We find that several airlines experienced substantial changes in environmental efficiency scores when flight delay is considered.Secondly,a tobit regression is used to explore whether the environmental factors of fleet age,ownership type,freight traffic,market share,and carrier type affect airlines’environmental efficiency.The results demonstrate that all of these factors significantly influence airline performance.

The evolution and determinants of Chinese property insurance companies’profitability:A DEA-based perspective

The property insurance industry grows fast in China and it is necessary to further investigate the profitability of the Chinese property insurance industry.This study investigates the evolution and determinants of the profitability of 53 Chinese property insurers during the year 2013-2017.Profitability is measured by profit ratio efficiency by data envelopment analysis(DEA)methodology and a profit ratio change index is applied to compare the performance of these insurers over different periods.Tobit regression models are used to investigate several influencing factors of profitability.The empirical results show the importance of proper arrangement of costs and revenues for an insurer and help to better understand the effect of firm size,age,and product specification on profitability.Some policy implications and suggestions are also proposed.