Construction of nearly orthogonal Latin hypercube designs

Latin hypercube designs have found wide application in computer experiments. A number of methods have recently been proposed to construct orthogonal Latin hypercube designs. In this paper, we propose an approach for expanding the orthogonal Latin hypercube design in Sun et al. (Biometrika 96:971–974, 2009) to a nearly orthogonal Latin hypercube design of a larger column size. The newly added part has half number of columns of the original part. It can be shown that the upper bound of the maximum correlation between any two distinct columns of the resulting design is very small. Our method also works for expanding any symmetric Latin hypercube designs.     

Scaling limits of two-dimensional percolation: an overview

We present a review of the recent progress on percolation scaling limits in two dimensions. In particular, we consider the convergence of critical crossing probabilities to Cardy's formula and of the critical exploration path to chordal stochastic Loewner evolution (SLE₆), the full scaling limit of critical cluster boundaries, and near-critical scaling limits.     

The disposition effect: a survey

The disposition effect is a well-recognized behavioral economic phenomenon which has been studied in numerous papers during the last three decades. Besides a literature review of the major theoretical, empirical, and experimental papers, the body of academic literature is subjected to a bibliometric analysis where all papers are taken into account which can be found via the search engine “EBSCOhost” (589 hits). This paper not only extensively describes the state of the art of research on the topic of the disposition effect. The combination of insights from a content analysis as well as a bibliometric analysis serves as a case study on the pattern of diffusion of research hypotheses and research methods. For example, it can be shown that the number of publications per year on the disposition effect remained relatively low subsequent to its discovery and only later started to substantially grow over time. On the other hand, the quality of papers, as approximated by the share of “A” journal articles per year, decreased over time.     

Unemployment and self-employment: a survey

The currently high level of unemployment emphasises the importance (in policy terms) of the potential contribution of a self employment alternative. Here the author examines the available UK evidence on the degree of movement from unemployment to self employment, the factors influencing this movement and the role of labour market information and training.     

Multivariate GARCH models: a survey

This paper surveys the most important developments in multivariate ARCH‐type modelling. It reviews the model specifications and inference methods, and identifies likely directions of future research. Copyright © 2006 John Wiley & Sons, Ltd.     

Discrimination in contests: a survey

The objective of this paper is to provide a comprehensive answer to some fundamental questions related to discrimination within the context of contests. For example, what forms of discrimination are possible? Can discrimination be justified? What mode of discrimination is expected? Does discrimination necessarily result in the elimination of polarization? How effective are the different modes of discrimination in inducing efforts (revenue)? How do the most widely studied contests based on an all-pay-auction and on a lottery compare under different modes of discrimination? Applying a contest-design approach, we examine four alternative types of discrimination that can be selected by a contest designer who maximizes the contestants’ efforts (his revenue). Our survey focuses on the leading principles of the separate and joint effective application of the alternative modes of direct, overt covert and head starts-discrimination that are assumed to be exercised under the widely studied family of (logit) contest success functions (CSFs). Whereas direct discrimination refers to differential taxation of the contested prize subject to a balanced-budget constraint, overt, covert and head starts-discrimination relate to structural discrimination that involves the parameters of the CSF. While the direct mode of discrimination is legally feasible, the structural modes of discrimination are more subtle and more difficult to implement and, sometimes, may even involve legal barriers.     

The expert problem: a survey

The survey is focused on the typical problems in information transmission from experts to non-experts. Attention is paid to the factors that can affect information disclosure in models that apply a game-theoretic approach to the use of professional advice. In the economic literature expertise is mainly analyzed as a special case of asymmetric information between expert and non-expert. The contributions are reviewed according to a double criterion, that takes into account both the preferences of the experts and the properties of communication. On one side, either the non-expert plays the role of a decision-maker, who chooses an action that is payoff-relevant for the expert, or the preferences of the expert directly depend on some measure of his reputation as a high-ability forecaster. On the other side, communication can range from pure cheap talk to completely verifiable messages.     

Equipment replacement policy: a survey

Over the past ten years there has been a considerable increase in application of theoretically correct measurement methods in determining the economic life of equipment. Approximately 89% of the firms surveyed have equipment replacement policies. The discounted rate of return method is the most widely used in determining the service life of equipment; the MAPI formula is not widely used. Difficulties in applying a replacement policy can be classified into three groups: operational, organizational, and economic. The problems mentioned most often are operational. In organizational difficulties there is usually a lack of coordination between staff and line managers. Economic problems are generally the limited funds available for equipment replacement. Formal educational programs are lacking for the development of equipment replacement managers. For the firms having replacement policies, individuals with engineering degrees are preferred over those in other disciplines for the management of the equipment replacement policy.     

Uniqueness in percolation theory

The possible uniqueness of the infinite cluster in percolation theory has been a subject of research for more then three decades. A number of important results have been proved in the last eight years and most of the question posed thirty years ago are answered nowadays. In this review paper, I shall give an account on the history of the subject plus recent developments. My goal is not only to mention the main results, but also to give some idea of the methods of proofs which are involved. I also discuss some applications and open problems.     

Two-stage stochastic integer programming: a survey

Stochastic integer programming is more complicated than stochastic linear programming, as will be explained for the case of the two-stage stochastic programming model. A survey of the results accomplished in this recent field of research is given.     

The theory of contests: a survey

This paper presents a survey of the theory of contests. This paper is an outgrowth of lecture notes of Ph.D. courses given in Carlos III University, Universitat Autònoma de Barcelona and Universidad de Málaga. I would especially like to thank to Carmen Beviá for her comments and suggestions and Matthias Dahm for allowing me free access to a joint paper and for correcting many mistakes and very helpful suggestions. I also thank Clara Eugenia García, Cristian Litan, Carlos Pimienta, Santiago Sánchez-Pages, Ramon Torregrosa, Galina Zudenkova and the students of this course for their helpful comments and CAICYT for research grant SEJ2005-06167/ECON.     

Consistent estimation of percolation quantities

We consider ordinary independent percolation on the integer lattice, and construct consistent estimators for most of the important quantities associated to this model. We also present some simulation results.     

Non-homogeneous servers in emergency medical systems: Practical applications using the hypercube queueing model

In this paper, we study the effects of considering homogeneous versus non-homogeneous servers in applications of the hypercube queueing model. This is important since approximate methods available for solving the model for homogeneous servers are computationally much less time-consuming than the exact methods required for the non-homogeneous case. Illustrative examples are initially presented to show the degree to which using homogeneous versus non-homogeneous servers can differ. Then, two ambulance deployment applications dealing with Brazilian emergency medical systems, in a city and along a highway, are analyzed. The basic operational characteristics of non-homogeneous systems were compared to the respective predictions produced under the simplifying assumption of homogeneous servers. It was found that, even when the degree of non-homogeneity of the servers is not highly significant, homogeneity may lead to poor predictions of the actual operational characteristics of non-homogeneous systems.     

Hospital material management in Taiwan: a survey

The new insurance policy that began in 1995 for all people in Taiwan and severe competition within the health care industry are some of the pressing issues forcing hospitals to improve their operational efficiency. A primary productivity improvement for hospitals is the reduction of the cost of material management because the materiel function on average controls 30-40 percent of the operating dollars in a Taiwan hospital. In this article, a fuzzy clustering method is used to classify the different types of materiel management systems within Taiwan hospitals. Inventory turnover rates and fill rates are compared among those different types of systems by using multivariate analysis of variance. The results show that the differences in both inventory turnover rates and fill rates are statistically significant among different material management systems.     

Categories of university-level entrepreneurship: a literature survey

Research into the nature, antecedents and effects of university-level entrepreneurship has grown due to the emergence of the university technology transfer phenomenon and the evolution of university's role in national innovation systems and economic development. From the literature survey, three research categories for university-level entrepreneurship are identified and examined namely entrepreneurial university, academic entrepreneurship and university technology transfer. Then, a framework depicting the relationship of the three research categories is developed and discussed. Lastly, recommendations are made for future research and analysis.     

Industrial relations in Northern Ireland: a survey

This survey finds that the legal and institutional framework and industrial relations practice in Northern Ireland have only been marginally affected by civil strife and continue to evolve in line with developments in Britain.     

Personnel scheduling in public systems: a survey

In many public systems efficiencies may be realized by improved personnel scheduling. This paper surveys the literature on personnel scheduling in the public domain. Two general problems are considered: the daily scheduling problem where hourly employee work day patterns are determined and the weekly scheduling problem where day off and day on work week patterns are constructed. The daily problem is discussed in terms of scheduling with and without simultaneous work assignment; and the weekly problem is dichotomized into those schedules based on cyclical personnel requirements and those that are not.     

The behavioral justification for public pensions: a survey

Unfunded public pension systems are primarily justified on grounds that many individuals lack sufficient capacity to appropriately save for retirement. We begin with a review of the known principle that a standard life-cycle/permanent-income consumer who discounts the future at an exponential rate can benefit from an unfunded public pension system only if the internal rate of return exceeds the private rate of return. However, a pay-as-you-go program with a below market internal rate can in fact improve lifetime utility if the consumer misestimates social security benefits, uses a hyperbolic discount function rather than the exponential function, uses a short planning horizon, behaves impulsively, or if a fraction of the population do no saving at all. A literature has consequently arisen to study how severe these behavioral defects need to be in order to justify a pay-as-you-go program. We survey this literature, and we conclude that the results are highly mixed as to whether an unfunded public pension that earns a below-market internal rate of return can be justified on grounds of shortsightedness in model economies. The challenge for this literature is that the conclusions crucially depend on the particular values of the preference parameters that are used in the simulation experiments, and these preference parameters are not observable, nor is there much consensus concerning the values that should be used in simulations. In fact, even when the analysis is confined to a small and reasonable space of the unobservable preference parameters, it is possible to reach nearly any policy conclusion. We offer some guidance for future work in this area.