Modelling of repairable systems with various degrees of repair

The availability of a stochastic repairable system depends on the failure behaviour and on repair strategies. In this paper, we deal with a general repair model for a system using auxiliary counting processes and corresponding intensities which include various degrees of repair (between minimal repair and perfect repair). For determining the model parameters we need estimators depending on failure times and repair times: maximum likelihood (ML) estimator and Bayes estimators are considered. Special results are obtained by the use of Weibull-type intensities and random observation times.     

A multilevel, identity-based approach to leadership development

A frontier of leadership development is examined involving the respective roles of levels-of-analysis and identity in constructing an integrated development system. An approach is described in which individual and relational leadership identities are the focus of developmental efforts at lower organizational levels (e.g., individual contributor and first-level supervisor) but collective identities become the focus at higher levels (e.g., general manager and above). The separate areas of levels-of-analysis and leader identities are first discussed in terms of their respective relevance to leadership development. These are then discussed jointly in elaborating on a proposed development approach that integrates across organizational levels as well as levels of development (i.e., leader development and leadership development). In developing collective leadership identities, processes that involve participants in engaging across boundaries (functional, hierarchical, geographical) are recommended.     

Interviewers,Interviewer Continuity,and Panel Survey Nonresponse

It is widely known that in practice, different interviewers have different response rates, though there has been no systematic examination of whether this is because of differences among interviewers or differences among those areas allocated to the interviewers (area effects), or both. Furthermore, the conventional wisdom in survey research suggests that it is advisable to have the same interviewers return to the same respondents in order to maintain good response rates in longitudinal surveys, though once again there has been very little documented experimental research to support this. This paper makes use of the interpenetrated sample design experiment in Wave 2 of the British Household Panel Study (BHPS) (i) to explore the effects of interviewers' background characteristics and years of experience on response rates, (ii) to identify and estimate the differential effects of interviewers on response rates and compare the magnitudes of area and interviewer effects, and (iii) to investigate the impact of interviewer continuity. The analysis is facilitated by the use of cross-classified multilevel modelling. The paper also looks at the issue of interviewer continuity qualitatively, through the impressions of the interviewers themselves.     

The economic costs of biological predation

This paper developes a bioeconomic model to analyse the economic losses from the reduced harvesting of prey species resulting from an increase in the stock of a natural predator. Examples of large mammals creating economic damage are whales and African elephants. The economic losses depend critically on the actual management of the prey stock, although the three measures we develop are equal when the stock is managed so as to maximize the sustained economic rent from the prey species. Predation losses are illustrated by the case of the Northeastern Atlantic Minke whale, where the estimate of the average predation cost per whale in 1991–1992 is between $US 1780 and $US 2370, using Norwegian cost and earnings data. A ten percent stock increase is estimated to cause a loss of almost $US 19 million to the fishers of the prey species. If half of this cost were assigned to Norway it would be equivalent to 2.8 and 6.7 percent of the gross profits of the Norwegian cod and herring fisheries, respectively.     

Asymptotic confidence bands for the estimated autocovariance and autocorrelation functions of vector autoregressive models

This paper provides closed-form formulae for computing the asymptotic covariance matrices of the estimated autocovariance and autocorrelation functions of stable VAR models by means of the delta method. These covariance matrices can be used to construct asymptotic confidence bands for the estimated autocovariance and autocorrelation functions to assess the underlying estimation uncertainty. The usefulness of the formulae for empirical work is illustrated by an application to inflation and output gap data for the U.S. economy indicating the existence of a significant short-run Phillips-curve tradeoff.First version received: November 2002/Final version received: September 2003     

Forecasting UK house prices: A time varying coefficient approach

Previous studies of UK house prices, developed from the demand and supply ofhousing or from the asset market approach have been poor in terms of robustness and ex-post forecasting ability. The UK housing market has suffered a number of structural changes, particularly since the early 1980s with substantial house price increases, financial market deregulation and the removal of mortgage market constraints through competition. Consequently, models which assume that the underlying data-generating process is stable and apply constant parameter techniques tend to suffer in terms of parameter instability. This article uses the Time Varying Coefficient (TVC) methodology where the underlying data-generating process in the UK housing market is treated as unstable. The estimation results of the TVC regression of UK house prices is compared with those obtained from three alternative constant parameter regressions. Comparisons of forecasting performance suggest the TVC regression out-performs forecasts from an Error Correction Mechanism (ECM), Vector Autoregressive (VAR) and an Autoregressive Time Series regression.     

Geometrical Interpretation of the Mean and the Constant in a Box-Jenkins Time Series Model

Certain manuals and computer programs mistakenly identify the mean with the constant in Box-Jenkins time series models. In this paper, it will be shown that (a) the mean and the constant have different values in autoregressive models, and (b) they have an algebraic and graphical relationship.     

贵州乡村生态旅游发展构想

本文论述了贵州乡村生态旅游开发的依据和必要性,分析了贵州乡村生态旅游开发的有利条件和存在的问题,阐述了贵州乡村生态旅游开发应遵循的原则。从旅游资源性质、游客感知方式及运作管理等不同侧面探讨了贵州乡村生态旅游开发的模式,提出了促进贵州乡村生态旅游持续健康发展的措施。     

环境艺术设计“课题制“教学模式实验

本文结合教学实践,就环境艺术设计教学中实施"课题制"教学模式进行了探索,着重对"课题制"教学模式的基本认识和运用进行了论述。