A concave pairwise fusion approach to subgroup analysis

An important step in developing individualized treatment strategies is to correctly identify subgroups of a heterogeneous population, so that specific treatment can be given to each subgroup. In this paper, we consider the situation with samples drawn from a population consisting of subgroups with different means, along with certain covariates. We propose a penalized approach for subgroup analysis based on a regression model, in which heterogeneity is driven by unobserved latent factors and thus can be represented by using subject-specific intercepts. We apply concave penalty functions to pairwise differences of the intercepts. This procedure automatically divides the observations into subgroups. We develop an alternating direction method of multipliers algorithm with concave penalties to implement the proposed approach and demonstrate its convergence. We also establish the theoretical properties of our proposed estimator and determine the order requirement of the minimal difference of signals between groups in order to recover them. These results provide a sound basis for making statistical inference in subgroup analysis. Our proposed method is further illustrated by simulation studies and analysis of the Cleveland heart disease dataset

Banking Reform and Efficiency in China: 1995-2008

Employing the one-step stochastic frontier analysis (SFA) approach, this paper examines bank efficiency in China, paying special attention to the ownership, selection effect and dynamic effects of governance changes on bank performance. Bank efficiency has improved over the data period 1995-2008. The estimated average cost and profit efficiencies are 74% and 63% respectively. Joint Stock Commercial Banks (JSCBs) and City Commercial Banks (CCBs) outperform State-owned Commercial Banks (SOCBs). The results suggest a strong selection effect for foreign investors. Foreign ownership participation has a negative effect on profit efficiency in the long-term while initial public offerings (IPOs) improve bank profitability in the short-term. The research findings have important implications on future bank reforms in China in the aftermath of the current financial crisis.SFA, Efficiency, Banking, China

Impact of Trade Facilitation on Export Competitiveness: a Regional Perspective

The present study, based on the experiences of China Customs, aims to identify good practices in enhancing export competitiveness through customs modernization. The paper examines the link between customs operations and export competitiveness, reviews overall principles and patterns for customs modernization, and proposes relevant models. It then examines the modernization of China Customs, including its objective, strategy, major initiatives and measures, as well as the overall impact of a modernized customs on export expansion.Customs, Export, Competitiveness, China

Airport Development and Regional Economic Growth in China

Air transport has experienced phenomenal growth in China over the last 30 years, but studies on China’s airport development are few. This paper aims to fill in this literature gap by focusing on the determinants of airport development in the Chinese regions using the most up-to-day and comprehensive data on China’s airports and their related economic and geographical variables. The empirical results based on an augmented production function indicate that airport development is positively related with economic growth, industrial structure, population density, and openness, but negatively related with ground transportation. The growth of airport transportation in the eastern region is slower than in the inland areas, implying a more significant substitution effect of air transport on ground transport in the less densely populated areas, irrespective of economic activities. The results have useful policy implications as any regional transportation development plan has to simultaneously consider the competitive and supplementary effects of both air and land transports in a specific location.Airport Development, Regional Economic Growth, China

The effects of governance changes on bank efficiency in China: A stochastic distance function approach

China has accelerated and deepened bank reform since it joined the WTO in 2001. Employing a stochastic distance function, this paper investigates the technical efficiency of banks and examines the static, selection and dynamic effects of governance changes on bank efficiency in China for the period 1995-2005. Our results show that bank efficiency has been improved and state-owned banks still perform poorly except for a noticeable improvement from 2003. Strong selection effects are found from both the foreign acquisition and going-public reform strategies. Foreign acquisition may benefit bank efficiency in the long run, but going-public appears to have just some short run effects. One obvious policy implication is that foreign competition is beneficial to China 's on-going bank reform, and going-public is just a means to allow effective foreign competition.Distance function, Efficiency, Banking, China