http://repub.eur.nl/res/aut/3301/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/37687/ 2012-08-01T00:00:00Z To study preferences, respondents to a survey are usually asked to select their most preferred option from a set. Preferences can be estimated more efficiently if respondents are asked to rank all alternatives. When some respondents are unable to perform the ranking task, using the complete ranking may lead to a substantial bias. We introduce a model which endogenously describes the ranking capabilities of individuals. Estimated preferences based on this model are more efficient when at least some individuals are able to rank more than one item, and they do not suffer from biases due to ranking inabilities of respondents. http://repub.eur.nl/res/pub/22208/ 2011-01-01T00:00:00Z We develop a panel model for regional house prices, for which both the cross-section and the time series dimension is large. The model allows for stochastic trends, cointegration, cross-equation correlations and, most importantly, latent-class clustering of regions. Class membership is fully data-driven and based on the average growth rates of house prices, and the relationship of house prices with economic growth. We apply the model to quarterly data for the Netherlands. The results suggest that there is convincing evidence for the existence of two distinct clusters of regions with pronounced differences in house price dynamics. http://repub.eur.nl/res/pub/22054/ 2010-11-01T00:00:00Z Background: Angiotensin II receptor blockers have been proven to be beneficial in left ventricular failure. In patients with a morphologic right ventricle supporting the systemic circulation, its efficacy has not yet been established. Methods: We designed a multicenter, prospective, randomized, double-blind, placebo-controlled trial studying the effect of valsartan in patients with a systemic right ventricle due to a congenitally or surgically corrected transposition of the great arteries. The primary end point is the change in right ventricular ejection fraction as measured by cardiovascular magnetic resonance or multidetector row cardiac computed tomography in case of pacemaker patients. Conclusion: This large prospective, double-blind, randomized, placebo-controlled trial will establish the role of angiotensin II receptor blockers (valsartan) in the treatment of patients with a systemic right ventricle. http://repub.eur.nl/res/pub/16185/ 2009-07-02T00:00:00Z Finite mixture distributions are a weighted average of a ¯nite number of distributions. The latter are usually called the mixture components. The weights are usually described by a multinomial distribution and are sometimes called mixing proportions. The mixture components may be the same type of distributions with di®erent parameter values but they may also be completely di®erent distributions (Everitt and Hand, 1981; Titterington et al., 1985). Therefore, ¯nite mixture distributions are very °exible for modeling data. They are frequently used as a building block within many modern econometric models. The speci¯cation of the mixture distribution depends on the modeling problem at hand. In this thesis, we introduce new applications of ¯nite mixtures to deal with several di®erent modeling issues. Each chapter of the thesis focusses on a speci¯c modeling issue. The parameters of some of the resulting models can be estimated using standard techniques but for some of the chapters we need to develop new estimation and inference methods. To illustrate how the methods can be applied, we analyze at least one empirical data set for each approach. These data sets cover a wide range of research ¯elds, such as macroeconomics, marketing, and political science. We show the usefulness of the methods and, in some cases, the improvement over previous methods in the literature. http://repub.eur.nl/res/pub/15112/ 2009-03-16T00:00:00Z We develop a new Bayesian approach to estimate the parameters of a latent-class model for the joint clustering of both modes of two-mode data matrices. Posterior results are obtained using a Gibbs sampler with data augmentation. Our Bayesian approach has three advantages over existing methods. First, we are able to do statistical inference on the model parameters, which would not be possible using frequentist estimation procedures. In addition, the Bayesian approach allows us to provide statistical criteria for determining the optimal numbers of clusters. Finally, our Gibbs sampler has fewer problems with local optima in the likelihood function and empty classes than the EM algorithm used in a frequentist approach. We apply the Bayesian estimation method of the latent-class two-mode clustering model to two empirical data sets. The first data set is the Supreme Court voting data set of Doreian, Batagelj, and Ferligoj (2004). The second data set comprises the roll call votes of the United States House of Representatives in 2007. For both data sets, we show how two-mode clustering can provide useful insights. http://repub.eur.nl/res/pub/17040/ 2009-01-01T00:00:00Z Objective: Microbiological examination of donated human cardiac tissue is a necessary procedure for Heart Valve Banks to determine the biological safety of preserved allografts. Test protocols must be validated to prevent false-negative outcomes that pose a risk of infection to recipients of the tissue. The Heart Valve Bank in Rotterdam evaluated a validated, alternative entry test for donated tissues to compare the performance of its standard microbiological examinations. Methods: Samples of explanted heart transport medium from 275 donors were examined for the presence of microorganisms using blood culture flasks (standard test) and fluid thioglycolate medium (alternative test). Results were compared with the outcome of microbiological assessment of subvalvular myocardial fragments and the cryoprotective medium that were collected before and after treatment of the grafts with antibiotics, respectively. Results: Microorganisms, mainly skin flora, were detected in transport medium of 177 hearts (64%). The alternative validated culture method detected a growth in 80 transport medium samples that was not identified by the standard method. Microorganisms were only identified in the cultivated cardiac tissue fragments from 56 donors (20%). After antibiotic treatment of the tissue, microorganisms could still be encountered in cryoprotective medium samples from 55 donors (20%). Most of the contaminants in these final samples were identified as Propionibacterium species and Corynebacterium species and had already been detected in the transport medium by the alternative validated culture method. Conclusions: The use of blood culture flasks for microbiological assessment of non-blood liquid media and the cultivation of myocardial tissue fragments may hamper detection of certain microorganisms and therefore provide less complete information about microbiological safety. Heart Valve Banks may want to review their microbiological examination and decontamination procedures regarding the ability to detect and eliminate anaerobic skin flora, respectively. http://repub.eur.nl/res/pub/13156/ 2008-09-01T00:00:00Z Empirical analysis of individual response behavior is sometimes limited due to the lack of explanatory variables at the individual level. In this paper we put forward a new approach to estimate the effects of covariates on individual response, where the covariates are unknown at the individual level but observed at some aggregated level. This situation may, for example, occur when the response variable is available at the household level but covariates only at the zip-code level. We describe the missing individual covariates by a latent variable model which matches the sample information at the aggregate level. Parameter estimates can be obtained using maximum likelihood or a Bayesian analysis. We illustrate the approach estimating the effects of household characteristics on donating behavior to a Dutch charity. Donating behavior is observed at the household level, while the covariates are only observed at the zip-code level. http://repub.eur.nl/res/pub/11723/ 2007-12-01T00:00:00Z We develop a parsimonious panel model for quarterly regional house prices, for which both the cross-section and the time series dimension is large. The model allows for stochastic trends, cointegration, cross-equation correlations and, most importantly, latent-class clustering of regions. Class membership is fully data-driven and based on (i) average growth rates of house prices, (ii) the propagation of shocks to house prices across regions, also known as the ripple effect, and (iii) the relationship of house prices with economic growth and other variables. Applying the model to quarterly data for the Netherlands, we find convincing evidence for the existence of two distinct clusters of regions, with pronounced differences in house price dynamics. http://repub.eur.nl/res/pub/8533/ 2007-02-06T00:00:00Z In this paper we consider the situation where one wants to study the preferences of individuals over a discrete choice set through a survey. In the classical setup respondents are asked to select their most preferred option out of a (selected) set of alternatives. It is well known that, in theory, more information can be obtained if respondents are asked to rank the set of alternatives instead. In statistical terms, the preferences can then be estimated more efficiently. However, when individuals are unable to perform (part of) this ranking task, using the complete ranking may lead to a substantial bias in parameter estimates. In practice, one usually opts to only use a part of the reported ranking. In this paper we introduce a latent-class rank-ordered logit model in which we use latent segments to endogenously identify the ranking capabilities of individuals. Each segment corresponds to a different assumption on the ranking capability. Using simulations and an empirical application, we show that using this model for parameter estimation results in a clear efficiency gain over a multinomial logit model in case some individuals are able to rank. At the same time it does not suffer from biases due to ranking inabilities of some of the respondents. http://repub.eur.nl/res/pub/7453/ 2006-02-20T00:00:00Z Empirical analysis of individual response behavior is sometimes limited due to the lack of explanatory variables at the individual level. In this paper we put forward a new approach to estimate the effects of covariates on individual response, where the covariates are unknown at the individual level but observed at some aggregated level. This situation may, for example, occur if the response variable is available at the household level but covariates only at the zip-code level. We describe the missing individual covariates by a latent variable model which matches the sample information at the aggregate level. Parameter estimates can be obtained using maximum likelihood or a Bayesian approach. We illustrate the approach estimating the effects of household characteristics on donating behavior to a Dutch charity. Donating behavior is observed at the household level, while the covariates are only observed at the zip-code level. http://repub.eur.nl/res/pub/19275/ 2006-02-01T00:00:00Z There is a large literature evaluating job-training programmes. In this paper, we evaluate three such job-training programmes that are used in Slovakia. Individuals participating in a job-training programme during their unemployment spell are usually not a random subsample of the population. To determine the treatment effect of a job-training programme on unemployment duration, one has to correct for this selection effect. Therefore, we use a multivariate mixed proportional hazard-type model to describe the hazard of getting a job simultaneously with the hazard of entering a programme. We allow for a heterogeneous treatment effect and for the treatment effect to vary over time. Furthermore, we add the monthly unemployment rate as a time-varying explanatory variable. The estimation results show that two of the three programmes shorten the unemployment duration quite substantially. http://repub.eur.nl/res/pub/10112/ 2003-01-01T00:00:00Z AIMS: According to 'the continuum of resistance model' late respondents can be used as a proxy for non-respondents in estimating non-response bias. In the present study, the validity of this model was explored and tested in three surveys on alcohol consumption. METHODS: The three studies collected their data by means of mailed questionnaires on alcohol consumption whereby two studies also performed a non-response follow-up. RESULTS: Comparisons of early respondents, late respondents and non-respondents in one study showed some support for 'the continuum of resistance model', although another study could not confirm this result. Comparison of alcohol consumption between three time response groups showed no significant linear pattern of differences between response waves. CONCLUSIONS: The hypothesis that late respondents are more similar to non-respondents than early respondents, could not be confirmed or rejected. Repeated mailings are effective in obtaining a greater sample size, but seem ineffective in improving the representativeness of alcohol consumption surveys. http://repub.eur.nl/res/pub/1994/ 2003-01-01T00:00:00Z The paper investigates the relationship between job satisfaction and labour market transitions. Using a multinomial logit model, a model is estimated on the basis of individual data in which transitions are explained from individual characteristics, job characteristics, dissatisfaction with the job and discrepancies between the actual and the desired number of hours worked. Transitions can be changes in the hours worked, changes to a different job and/or employers, or combinations. Furthermore, people may lose their job and leave employment out of free will. The model has been estimated for three categories of workers according to the number of hours worked. The results show that both dissatisfaction with the job and discrepancies with respect to the hours worked have a significant impact on transition probabilities. Contrary to what is sometimes believed there is no structural increase in transition probabilities. We are still far away from a ‘transtional labour market’. The paper also shows that transitions significantly increase job satisfaction. However, despite the strong improvement in the labour market situation in the 1990s, the percentage of the workers experiencing a dscrepancy between the actual and the desired number of hours has not diminished.