Simulation driven inferences for multiply imputed longitudinal datasets*

In this article, we demonstrate by simulations that rich imputation models for incomplete longitudinal datasets produce more calibrated estimates in terms of reduced bias and higher coverage rates without duly deflating the efficiency. We argue that the use of supplementary variables that are thought to be potential causes or correlates of missingness or outcomes in the imputation process may lead to better inferential results in comparison to simpler imputation models. The liberal use of these variables is recommended as opposed to the conservative strategy.     

The Case of the Missing Pollution Haven Hypothesis

One particularly vexing puzzle for economists and policymakers over the past several decades concerns the empirical significance of the theoretically predicted pollution haven hypothesis. While neoclassical theory and conventional wisdom both surmise that local economies will suffer deleterious effects from stricter environmental regulations, empirical studies have largely failed to validate such claims. This study utilizes the method of matching to show that the impact of stricter regulation is heterogeneous spatially, varying systematically based on location-specific attributes. Previous studies that assume a homogenous response may therefore inadvertently mask the overall impact of more stringent regulations by pooling unaffected and affected regions.JEL Classification: Q25, Q28, H00, L51, R1The authors wish to thank to Michael Crew, Anthony Heyes, an anonymous referee, Werner Antweiler, Randy Becker, Wayne Gray, Shelby Gerking, Michael Greenstone, Vern Henderson, and Arik Levinson. Participants at various university seminars and conferences also lent useful insights to this line of research.     

Economic progress and skill obsolescence with network effects

Summary. We construct an OLG model with network effects to examine skill obsolescence when individuals can choose technological vintages. In the absence of transfer payments, some regions of the parameter space have unique stationary equilibria, others have unique cyclical equilibria, and others have multiple stationary equilibria. All equilibria are Pareto efficient. However, rat race equilibria can exist in which all agents currently alive prefer a slower rate of progress than occurs in equilibrium. When contemporaneous transfers are allowed, equilibria are unique everywhere, but a cycle still exists, and a rat race can still arise in equilibrium. Allowing intertemporal transfers (debt) ensures that all equilibria are stationary. In the relevant parameter range, the introduction of debt can eliminate cycles and increase the long-run growth rate. No rat race equilibria exist when debt is allowed.Received: 3 January 2002, Revised: 3 June 2004, JEL Classification Numbers: 041, J24, O33. Correspondence to: Ian P. KingEarly versions of this paper were presented at the West Coast Macro Workshop, the Mid-West Macro Meetings, the Canadian Macroeconomics Study Group Meetings, and the Society for Economic Dynamics Meetings. We would like to thank V. V. Chari, Merwan Engineer, Don Ferguson, John Hillas, John Knowles, Dan Peled, Dan Usher, Linda Welling and Julian Wright for helpful comments. We are especially grateful to an anonymous referee for some very useful and substantive comments.     

中医体质辨识结合六味地黄汤治疗老年性阴道炎患者的临床效果

目的探讨中医体质辨识结合六味地黄汤治疗老年性阴道炎患者的临床效果。方法选取2017年6月至2018年6月沈阳市大众医院收治的老年性阴道炎患者104例作为研究对象,随机分为对照组和观察组,每组52例。对照组采用常规治疗方法,观察组在常规治疗基础上采取中医体质辨识结合六味地黄汤的治疗方法。比较两组的治疗效果,以及治疗前后症状体征改善情况、阴道健康状况。结果观察组治疗有效率为96.15%,高于对照组的73.08%,差异有统计学意义(P<0.05)。两组治疗前症状体征积分比较,差异无统计学意义(P>0.05);治疗后,观察组带下量(0.93±0.19)分、白带异味(0.65±0.24)分、阴道灼热(0.63±0.20)分、外阴瘙痒(0.71±0.25)分,低于对照组,差异有统计学意义(P<0.05)。两组治疗前阴道健康积分比较,差异无统计学意义(P>0.05);治疗后,观察组阴道黏膜(1.01±0.38)分、阴道湿润(0.95±0.33)分、阴道弹力(1.32±0.34)分、阴道pH值(0.67±0.36)分、阴道清洁度(0.54±0.25)分,低于对照组,差异有统计学意义(P<0.05)。结论在老年性阴道炎的治疗中,采取中医体质辨识结合六味地黄汤的治疗方法,能够提高治疗有效率,改善症状体征及阴道健康,临床效果显著。     

Model selection in random effects models for directed graphs using approximated Bayes factors

With the development of an MCMC algorithm, Bayesian model selection for the p ₂ model for directed graphs has become possible. This paper presents an empirical exploration in using approximate Bayes factors for model selection. For a social network of Dutch secondary school pupils from different ethnic backgrounds it is investigated whether pupils report that they receive more emotional support from within their own ethnic group. Approximated Bayes factors seem to work, but considerable margins of error have to be reckoned with.     

The Dynamics of Capital Structure in Transition Economies

This paper uses a dynamic unrestricted capital structure model to examine the determinants of the private companies' target financial leverage and the speed of adjustment to it in two transition economies, the Czech Republic and Bulgaria. We explicitly model the adjustment of companies' leverage to a target leverage, and this target leverage is itself explained by a set of factors. The panel data methodology combines cross-section and time-series information. The results indicate that the Bulgarian corporate credit markets were less supply -constrained than those of the Czech Republic during the period under investigation. Bulgariancompanies adjusted much faster to the target leverage than Czech firms. The speed ofadjustment related positively to the distance between target and observed ratio for Bulgarian companies while the relationship was neutral for Czech companies. The conservative policies of Czech banks and the exposure control were likely responsible for the slower adjustment among the larger companies while the opposite were true for Bulgarian banks and companies.     

Nonresponse Bias and Stimulus Effects in the Dutch National Election Study

Bias is a much-debated issue in survey research. Answer effects (respondents claim to have behaved differently than they did in reality), nonresponse bias (nonrespondents differ on important variables from the respondents) and stimulus effects (by participating in a previous wave of a study, respondents change their behavior or attitude) can seriously distort the results of survey research. By using data from the 1998 Dutch National Election Study the authors show that the results of election research can indeed be affected by bias. Not only are significant effects found in the distribution of political attitude and voting behavior variables as a result of both nonresponse bias and stimulus effects, it is also shown that relations between variables change as a result of bias.     

山区工业化与山区环境协调发展研究──以浙江山区为例

根据发展经济学和环境经济学理论，研究山区工业化进程及其外部效果，剖析山区环境问题产生的机理和要素，探讨山区环境与经济协调发展的有效对策。     

Risk and Capital Structure in the Regulated Firm

This paper studies the role of capital structure in a regulated firm. We show that it affects the prices set by the regulator, the expected price being lower the higher the proportion of debt finance. However, when debt is increased beyond a certain level, the benefit of lower expected prices is offset by their increased variability. We also study the socially preferred capital structure. This is such that consumers carry some risk, in the form of higher prices in adverse economic conditions.     

我国旅游价格管理：现状、改革背景与政策分析

旅游业发展是一项复杂的系统工程，需要各相关行业和各项政策措施的配套协调。由于旅游价格的杠杆效应，如何应对入世给我国旅游业带来的挑战，改革并完善与国际接轨的旅游价格管理新体制是每一个旅游价格管理工作者应当思考的现实问题。