Estimating Engel curves under unit and item nonresponse

This paper estimates food Engel curves using data from the first wave of the Survey on Health, Aging and Retirement in Europe (SHARE). Our statistical model simultaneously takes into account selectivity due to unit and item nonresponse, endogeneity problems, and issues related to flexible specification of the relationship of interest. We estimate both parametric and semiparametric specifications of the model. The parametric specification assumes that the unobservables in the model follow a multivariate Gaussian distribution, while the semiparametric specification avoids distributional assumptions about the unobservables. Copyright © 2011 John Wiley & Sons, Ltd.     

An item response model with single peaked item characteristic curves: The PARELLA model

In this paper an item response model (the PARELLA model) designed specifically for the measurement of attitudes and preferences will be introduced. In contrast with the item response models currently used (e.g. the Rasch model and, the two and three parameter logistic model) the item characteristic curve is single peaked instead of monotonically increasing. The model and its properties will be introduced. After this the consequences of these properties for the item writing stage, the evaluation of the concordance of data and model, and the applicability of the model will be discussed. The paper is finished with an example concerning the measurement of change in the attitude in the car-environment issue.     

Citation analysis in research on differential item functioning

This paper offers a first approach to the study of citing behaviour in the literature on differential item functioning (DIF) and provides new information about the main characteristics that define that behaviour. With a focus on articles listed in the Web of Science for the period 1975–2000, the present research considers the number of self-citations included in each paper with respect to other bibliometric indicators such as year of publication, the number of signatories to a paper, author’s country of origin and the journal in which it was published. In general terms it can be concluded that in studies of DIF the mean percentage of self-citations is around 11%, this figure remaining stable over time; there is a positive correlation between the number of signatories to an article and the number of self-citations. This paper has offered a first approach to the study of citing behaviour in the literature on DIF.     

Relevance and advantages of using the item response theory

The item response theory (IRT) also known as latent trait theory, is used for the development, evaluation and administration of standardized measurements; it is widely used in the areas of psychology and education. This theory was developed and expanded for over 50 years and has contributed to the development of measurement scales of latent traits. This paper presents the basic and fundamental concepts of this IRT and a practical example of the construction of scales is proposed to illustrate the feasibility, advantages and validity of IRT through a known measurement, the height. The results obtained with the practical application of IRT confirm its effectiveness in the evaluation of latent traits.     

对项目管理的透析

从2001年四季度以来,从报上不时可以看到各种类型的项目管理的知识培训,对项目管理本科与硕士教程的招生,以及国际项目管理专业资质认证等信息.对这一新的知识传播、吸取、应用的热点,笔者以为其有前景,但不宜急功近利.     

How to examine construct validity of item banks

In this study data is brought to support an approach for assuring the content validity of item banks and for examining their construct validity. The method is an application of Guttman's concept of using mapping sentences for theory construction in the domain of “simple fraction’. The construct validity of the theory used for the creation of the item bank was tested by selecting two samples of items which are referenced in the same structuple (criterion). The Yule weak monotonicity coefficients of the items' connections were calculated and represented in two different matrices and in two different space diagrams. The results show clearly a similarity in both the structure of the space diagrams of any two parallel samples and in the partition of the points into regions, i.e., regions according to the classification of the items represented by them on the basis of the facets defined by the mapping sentences. Consequently, it may be concluded that the results support the construct validity of the theory on the basis of which the bank has been created.     

Vintage human capital and learning curves

I study a vintage-human-capital model in which long-lived workers accumulate human capital following an exogenous learning curve. Different skill levels inside a vintage are complementary in production; this makes the ex ante homogeneous workers enter different vintages. The continuous-time framework allows me to study the timing decision for the technology phase-out differentially and to derive sharp characterization for wages and the distribution of workers in the dying technology. I show how to posit and solve a planner's problem and construct equilibrium in this way. Consistent with empirical evidence, I show that the experience premium is always positive but diminishes as a technology ages. The connection between workers' learning curves and the technology's progress curve is characterized.     

咨询项目 让人满意不容易

对企业管理咨询服务而言,衡量其成功与否的标准,归根到底就是一个满意度的问题。这种满意度并不是接受咨询企业的满意度,而是企业与咨询公司双方同时获得的满意度。     

Evaluating and tracking qualitative content coder performance using item response theory

Content analysis of traditional and social media has a central role in investigating features of media content, measuring media exposure, and calculation of media effects. The reliability of content coding is usually evaluated using “kappa-centric” agreement measures, but these measures produce results that aggregate individual coder decisions which obscure the performance of individual coders. Using a data set of 105 advertisements for sports and energy drinks media content coded by five coders, we demonstrate that Item Response Theory can track coder performance over time and give coder-specific information on the consistency of decisions over qualitatively coded objects. We conclude that IRT should be added to content analysts’ tool kit of useful methodologies to track and evaluate content coders’ performance.

     

On the analysis of multivariate growth curves

Growth curve data arise when repeated measurements are observed on a number of individuals with an ordered dimension for occasions. Such data appear frequently in almost all fields in which statistical models are used, for instance in medicine, agriculture and engineering. In medicine, for example, more than one variable is often measured on each occasion. However, analyses are usually based on exploration of repeated measurements of only one variable. The consequence is that the information contained in the between-variables correlation structure will be discarded.  In this study we propose a multivariate model based on the random coefficient regression model for the analysis of growth curve data. Closed-form expressions for the model parameters are derived under the maximum likelihood (ML) and the restricted maximum likelihood (REML) framework. It is shown that in certain situations estimated variances of growth curve parameters are greater for REML. Also a method is proposed for testing general linear hypotheses. One numerical example is provided to illustrate the methods discussed. Received: 22 February 1999     

Zero expenditures and the estimation of engel curves

Over the brief interview periods typical of budget surveys (such as the U.K. Family Expenditure Survey) households' recorded expenditures are liable to be misleading indicators of their underlying consumption. Most starkly, a household may not be observed to purchase commodities that it nevertheless consumes. This paper considers the implications of such measurement errors for the estimation of demand systems, and derives a consistent estimator for the special case of linear Engel curves.     

谈建设项目工程造价的有效控制

本文简述了进行建设项目工程造价控制的必要性,从项目投资决策阶段、设计阶段、招投标阶段、工程实施阶段、竣工验收阶段等方面介绍了有效控制工程造价的措施.