ML– and semiparametric estimation in logistic models with incomplete covariate data

ML–estimation of regression parameters with incomplete covariate information usually requires a distributional assumption regarding the concerned covariates that implies a source of misspecification. Semiparametric procedures avoid such assumptions at the expense of efficiency. In this paper a simulation study with small sample size is carried out to get an idea of the performance of the ML–estimator under misspecification and to compare it with the semiparametric procedures when the former is based on a correct assumption. The results show that there is only a little gain by correct parametric assumptions, which does not justify the possibly large bias when the assumptions are not met. Additionally, a simple modification of the complete case estimator appears to be nearly semiparametric efficient.     

Panel unit root tests under cross-sectional dependence

In this paper alternative approaches for testing the unit root hypothesis in panel data are considered. First, a robust version of the Dickey-Fuller t -statistic under contemporaneous correlated errors is suggested. Second, the GLS t -statistic is considered, which is based on the t -statistic of the transformed model. The asymptotic power of both tests is compared against a sequence of local alternatives. To adjust for short-run serial correlation of the errors, we propose a pre-whitening procedure that yields a test statistic with a standard normal limiting distribution as N and T tends to infinity. The test procedure is further generalized to accommodate individual specific intercepts or linear time trends. From our Monte Carlo simulations it turns out that the robust OLS t -statistic performs well with respect to size and power, whereas the GLS t -statistic may suffer from severe size distortions in small and moderate sample sizes. The tests are applied to test for a unit root in real exchange rates.     

企业集团母子公司财务控制系统构建研究

企业集团是以产权关系为纽带 ,由众多企业法人共同组成的联合体。企业集团母子公司财务控制系统是企业集团核心管理内容之一。笔者通过自身的工作经验并结合理论研究认为 :企业集团母子公司财务控制系统是由财务人员控制系统、财务制度控制系统、财务目标控制系统和财务信息控制系统等构建的有机整体 ,企业集团管理当局应提供良好的人文环境和机制环境 ,保证其高效、及时、完整、良好地运行 ,保持企业集团的可持续发展 ,才能实现企业集团价值最大化     

矿区生态经济若干问题探讨

本文着重探讨了矿区资源开发中生态经济系统的特征；铜矿资源的珍贵性；矿区自然资源和生态环境以及劳动力资源的脆弱易损性；露采优先方针的重要性；矿区生态、经济、社会三者效益的统一性；21世纪采矿与环境协调发展的新概念和新技术、新工艺。     

Seasonal decomposition and forecasting of telecommunication data: A comparative case study

In this paper, forecasting models for the monthly outgoing telephone calls in a University Campus are presented. The data have been separated in the categories of international and national calls as well as calls to mobile phones. The total number of calls has also been analyzed. Three different methods, namely the Seasonal Decomposition, Exponential Smoothing Method and SARIMA Method, have been used. Forecasts with 95% confidence intervals were calculated for each method and compared with the actual data. The outcome of this work can be used to predict future demands for the telecommunications network of the University.     

Linking Public Investment to Private Investment. The Case of Spanish Regions

Public investment constitutes one of the main instruments of regional policies. The existence of a direct link between infrastructure and regional income per capita is usually accepted. Literature also describes a positive effect of public investment on private capital accumulation. This paper seeks to provide new empirical evidence on this latter relationship for the case of Spanish regions over the period 1965–1997 using panel data methodology. The results show a positive effect of productive and social public investment (especially in education) on private investment. The spillover effects generated by the productive infrastructures located in other regions do not seem to encourage the private investment in neighbouring regions. Public consumption and interest rate exert a negative influence on private capital accumulation. These results are robust to changes in the econometric specification.     

Web数据挖掘中XML技术的应用研究

随着网络技术的发展,网上的信息资源越来越丰富,怎样对Web上海量的数据信息进行深层次的应用成了当今数据库技术的研究热点。文章针对Web上数据的特点和目前Web数据挖掘存在的挑战,结合XML语言的技术特点,主要探讨了XML技术在Web数据挖掘中的重要应用。     

The price relationship between organic and non-organic vegetables in the U.S.: evidence from Nielsen scanner data

This study investigates price relationships between organic and conventional carrots, tomatoes, and lettuce in the U.S. utilizing Nielsen scanner data from 2006–2015. We employ a threshold vector error correction model (TVECM), threshold vector autoregressive model (TVAR), and threshold cointegration test to test whether market integration exists between organic and conventional vegetables as well as the existence of asymmetric price transmission. The results find positive long-run relationships between organic and conventional prices of carrots and tomatoes and show the existence of asymmetric price transmission in price pairs of lettuce and tomatoes. Our findings suggest that the price relationship between organic and conventional vegetables varies by characteristics, such as shelf life, volatility in the price premium, and substitutability.     

The Practice Boundaries of Advanced Practice Nurses: An Economic and Legal Analysis

The purpose of this study is to examine the effects of State regulation that determines the extent of professional independence of advanced practice nurses (APNs). We find that in States where APNs have acquired a substantial amount of professional independence, the earnings of APNs are substantially lower, and those of physicians assistants (PAs) are substantially higher, than in other States. These results are striking since PAs are in direct competition with APNs; the only real operational difference between these groups is that PAs are salaried employees who must work under the supervision of a physician. The implication is that physicians have responded to an increase in professional independence of APNs by hiring fewer APNs and more PAs. The finding that earnings of APNs decline when they attain more professional autonomy vis-à-vis physicians reinforces work by Sass and Nichols on physical therapists.The content is the responsibility of the authors and does not represent official positions of the Federal Reserve Bank of St. Louis or the Federal Reserve SystemJEL classification: I11, I18, J31, J44, L51     

我国地区经济差异与城市化水平关系的实证分析

对改革开放以来地区经济发展水平的差异以及建国以来全国及各省区的城市化的发展进程进行了描述,利用格兰杰因果关系检验,研究我国不同经济发展阶段中城市化水平与经济增长的因果关系, 并采用国际上流行的Panel data方法从多个角度对城市化与地区经济增长的关系进行了分析研究。结论是:城市化水平的提高对于落后地区经济增长的促进作用要高于经济发达地区。