Estimating panel data models in the presence of endogeneity and selection

We consider estimation of panel data models with sample selection when the equation of interest contains endogenous explanatory variables as well as unobserved heterogeneity. Assuming that appropriate instruments are available, we propose several tests for selection bias and two estimation procedures that correct for selection in the presence of endogenous regressors. The tests are based on the fixed effects two-stage least squares estimator, thereby permitting arbitrary correlation between unobserved heterogeneity and explanatory variables. The first correction procedure is parametric and is valid under the assumption that the errors in the selection equation are normally distributed. The second procedure estimates the model parameters semiparametrically using series estimators. In the proposed testing and correction procedures, the error terms may be heterogeneously distributed and serially dependent in both selection and primary equations. Because these methods allow for a rather flexible structure of the error variance and do not impose any nonstandard assumptions on the conditional distributions of explanatory variables, they provide a useful alternative to the existing approaches presented in the literature.     

Cointegration and the PPP and the UIP hypotheses: An application to the Spanish integration in the EC

The aim of this paper is to find some empirical evidence on Purchasing Power Parity (PPP) and Uncovered Interest Parity (UIP) in the Spanish case vis à vis the European Community for the period 1980–89. The main contribution of the paper is the aggregation of the variables corresponding to the countries that participate in the exchange rate mechanism of the European Monetary System. The results support the importance of the interest differential as an explanatory variable for the short-term adjustment to the PPP. The results follow from powerful estimation techniques, applied in the framework of a multivariate error-correction model using the maximum-likelihood procedure as developed by Johansen and Juselius (1992).     

A uniform weak law of large numbers under π-mixing with application to nonlinear least squares estimation

Abstract  In B ierens (1981) we have derived a uniform weak law of large numbers for stochastically stable processes with respect to a finite-dependent base. In this paper we show that this uniform weak law carries over to stochastically stable processes with respect to a, more general, φ-mixing base. This generalization will be used for relaxing the conditions for weak consistency and asymptotic normality of nonlinear least squares estimators.     

A passenger demand model for air transportation in a hub-and-spoke network

This paper develops an air passenger model that deals with city-pair demand generation and demand assignment in a single framework. Using publicly available and regularly collected panel data, the model captures both time series and cross-sectional variation of air travel demand. The empirical analysis finds that pattern of correlations among alternatives can be described by a three-level nested logit model. Fare, frequency, flight time, direct routing, on-time performance, income, and market distance have significantly effects on air demand. Correcting for the problem of endogenous air fares using instrumental variables yields more plausible estimates of price sensitivity and value of time.     

RISK MEASURES FOR NON-INTEGRABLE RANDOM VARIABLES

We show that when a real-valued risk measure is defined on a solid, rearrangement invariant space of random variables, then necessarily it satisfies a weak compactness, also called continuity from below, property, and the space necessarily consists of integrable random variables. As a result we see that a risk measure defined for, say, Cauchy-distributed random variable, must take infinite values for some of the random variables.     

Patrilocality and human capital accumulationEvidence from Central Asia1

Anthropologists estimate that 70 percent of human societies are patrilocal, meaning that adult sons reside with their parents, and that wives go to live with their husbands’ families upon marriage. Yet very little is known about how this widespread social norm influences intrahousehold resource allocation and, through this, economic development. This paper examines the effects of patrilocality on schooling and household educational expenditures in Tajikistan. To identify the causal effect of living in a three versus two generation household on these outcomes, exogenous variation in housing availability across communities is exploited. It is shown that the impacts of living in a three generation household are important for both school enrolment and for educational spending. The results suggest that one reason why patrilocal societies remain poorer than those with nuclear household norms is that three generation households make relatively few human capital investments in the youngest generation. Patrilocality, which probably evolved to solve coordination problems in agrarian societies, may thus be a cause rather than simply a correlate of low educational attainment in developing countries.     

客户信用管理理论在天然气营销中的应用

探讨了客户信用评价及管理的相关方法和理论，结合国内天然气市场的现状，提出了一种新的客户信用评价和管理的模式，并在实践中付诸应用，取得了良好的效果。客户信用管理体系的建立和应用，可为燃气市场的投资者、参与者、监管者提供一个有效的风险规避工具。     

Toward a sustainable conceptualization of dependent variables in entrepreneurship research

Entrepreneurship researchers have yet to explore the full range variance that occurs in entrepreneurial value creation because we have focused almost exclusively on financial performance as the dependent variable in our research. However, such arbitrary narrowness is not supported by research, which shows entrepreneurs to not focus exclusively on income maximization. Consistent with calls for an expanded view of the consequences of entrepreneurship, we develop a typology of entrepreneurship dependent variables that supports broadening the scope of entrepreneurship research to include economic, environmental and social value. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.     

物流上市公司系统风险与财务变量关系的实证分析

本文以33家中国物流上市公司1997年至2005年的年报资料为样本,采用多元回归方法,对中国物流行业系统风险和7个会计变量之间的关系进行了实证分析。研究结果表明:经营效率和盈利水平与系统风险负相关,而流动性、财务杠杆、公司规模和成长性与系统风险没有显著的相关性。