Multiple Imputation in Multivariate Problems When the Imputation and Analysis Models Differ

Bayesian multiple imputation (MI) has become a highly useful paradigm for handling missing values in many settings. In this paper, I compare Bayesian MI with other methods – maximum likelihood, in particular—and point out some of its unique features. One key aspect of MI, the separation of the imputation phase from the analysis phase, can be advantageous in settings where the models underlying the two phases do not agree.     

Foods produced using biotechnology: how does the law protect consumers?

This paper addresses the following subjects: biotechnology and consumers, concern about risks, consumer acceptance, labelling of foods produced using biotechnology, the legal approach to consumer protection, and consumer protection policies relating to biotechnology products in the European Union, the United States, Turkey and global institutions such as the Convention for Biological Diversity (CBD) and the World Trade Organisation (WTO). It is likely that biotechnology will gain ground much more rapidly in the twenty‐first century than in the past. Despite rapid, detailed and precise advances in gene technology, its applications have not been the received with a great deal of consumer enthusiasm. Consumers have approached genetically modified foods with considerable apprehension and opposition. Consumer concerns about bioengineered food products focus on the questions of human health, environmental and social risks and benefits. The most important stages in the process of marketing new foods produced using biotechnology are to demonstrate user need and consumer acceptance. Generally, the technical complexity of biotechnology makes it difficult for consumers to understand details of the product and the specific attributes of biotechnology applications. Scientific uncertainty, the nature of consumer concerns and general reluctance to accept biotechnology products, increase the importance of consumer protection. Legal protection is a very important factor in the solution of new social problems related to technological advances. More specifically, consumer and environmental law support consumer protection related to foods produced with biotechnology. The basic principles of consumer law can be re‐formulated as consumer rights. Environmental law is a new phenomenon, but precautionary principles and public participation in decision‐making for environmental law are relevant to consumer protection relating to bioengineered food products.     

Initial Public Offerings: CFO Perceptions

We examine four issues pertaining to initial public offerings (IPOs) using a survey of 438 chief financial officers (CFOs). First, why do firms go public? Second, is CFO sentiment stationary across bear and bull markets? Third, what concerns CFOs about going public? Fourth, do CFO perceptions correlate with returns? Results support funding for growth and liquidity as the primary reasons for IPOs. CFO sentiment is generally stationary in pre‐ and post‐bubble years. Managers are concerned with the direct costs of going public, such as underwriting fees, as well as indirect costs. We find a negative relation between a focus on immediate growth and long‐term abnormal returns.     

Endogenous Growth and Negative Externalities

Received March 5, 2001; revised version received August 5, 2002 Published online: April 30, 2003     

中国进口与经济增长关系的区域差异分析

利用面板数据对中国东、中、西部的进口额和GDP增长关系进行的实证研究。在短期内，GDP增长对进口额影响最小是中部地区，在长期，西部GDP增长对进口额影响最大。中国经济增长对拉动世界经济增长起了十分重要的作用，中国经济增长减速也会影响全球经济。     

Comparative Advantage in Demand: Experimental Evidence of Preferences for Genetically Modified Food in the United States and European Union

The United States (US) exports more than US$6 billion in agricultural commodities to the European Union(EU) each year, but one issue carries the potential to diminish this trade: use of biotechnology in food production. The EU has adopted more stringent policies towards biotechnology than the US. Understanding differences in European and American policies towards genetically modified (GM) foods requires a greater understanding of consumers’ attitudes and preferences. This paper reports results from the first large‐scale, cross‐Atlantic study to analyse consumer demand for genetically modified food in a non‐hypothetical market environment. We strongly reject the frequent if convenient assumption in trade theory that consumer preferences are identical across countries: the median level of compensation demanded by English and French consumers to consume a GM food is found to be more than twice that in any of the US locations. Results have important implications for trade theory, which typically focuses on differences in specialization, comparative advantage and factor endowments across countries, and for on‐going trade disputes at the World Trade Organization.     

RESEARCH NOTE: ERRORS IN THE OCTOBER HOUSEHOLD SURVEY 1994 AVAILABLE FROM THE SOUTH AFRICAN DATA ARCHIVE1

The on‐line electronic documentation supplied with the 1994 October Household Survey by the South African Data Archive (SADA) appears to be incorrect. In particular, the electronic version of the questionnaire does not correspond to the hard copy in the possession of the author. The most serious error is that the race classification in the electronic copy is different from the classification on the hard copy. Researchers relying on the electronic copy will erroneously interchange the categories “Coloured”, “White” and “Black”. This could lead to seriously misleading analyses. The reason for this mistake can probably be attributed to a retyping of the questionnaire using the 1993 OHS as a template.     

Web数据挖掘技术探索与应用

Web数据挖掘是当今世界上的热门研究领域,本文从Web数据挖掘的定义开始分析研究Web数据挖掘的难点、过程等相关技术,并计论其在电子商务领域中的相关应用。     

On the Role of Weight Restrictions in Data Envelopment Analysis

This paper examines the role that weight restrictions play in Data Envelopment Analysis (DEA). It is argued that the decision to include a factor (input or output) in a DEA model represents an implicit judgement that the factor has a non-trivial weight. It therefore seems perverse to allow DEA to assign a trivial weight to that factor in assessing the efficiency of a unit. There is therefore a strong case for imposing restrictions on factor weights. However, many existing methods of weight restriction are in practice unwieldy. This paper proposes an alternative approach we term contingent weight restriction which is both practical and intellectually consistent with the DEA philosophy. The paper explores the implications of alternative methods of weight restriction using simulated data from a well known production process.     

Productive Efficiency of the Swine Industry in Hawaii: Stochastic Frontier vs. Data Envelopment Analysis

Improving productive efficiency is an increasingly important determinant of the future of the swine industry in Hawaii. This paper examines the productive efficiency of a sample of swine producers in Hawaii by estimating a stochastic frontier production function and the constant returns to scale (CRS) and variable returns to scale (VRS) output-oriented DEA models. The technical efficiency estimates obtained from the two frontier techniques are compared. The scale properties are also examined under the two approaches. The industry's potential for increasing production through improved efficiency is also discussed.