Πλοήγηση ανά Επιβλέπων "Vasdekis, V."
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Τεκμήριο A comprehensive analysis of clinical longitudinal data using linear mixed-effects models: repeaded measurements we collected on HIV positive patients. Competing models were contrasted for their appropriateness on examing the effects of drug treatments to the severity of HIV infection.(Athens University of Economics and Business, 02-2005) Balta, Vassiliki K.; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Covariance estimators for generalized estimating equations in longitudinal analysis with small samples(20-06-2017) Barazian, Mari; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.The Generalized Estimating Equations (GEE) statistical method is a simple andeffcient approach to estimate the regression coeffcient of a marginal model forcorrelated responses when the associational structure is regarded as a \nuisance". Itsmost common use is to fit marginal models for longitudinal data in several fields such asbiomedical studies and social sciences. The most attractive feature of the GEEmethodology is that consistent estimates for marginal regression coeffcients areobtained even if the correlation structure is misspecified. However, the techniquerequires that the sample size is large. The variance-covariance matrix of the regressionparameter coeffcients is often estimated by the so-called \sandwich" variance estimator,which is robust and performs well when the size of the sample is large. However, whenthe sample size is small, the \sandwich" estimator does not have a good performance.Specifically, in that case, bias and ineffciency appear. The main goal is to find ways inorder to decrease the bias and improve the effciency. For this reason, some recentlydevelopped modified variance estimators have been proposed. The current GEEmethodology focuses on the modeling of the working correlation matrix assuming aknown variance function. However, Wang, Y.-G., Lin, X. and Zhu, M. (2005) showedthat the correct choice of the correlation structure may not necessarily improve theestimation effciency for the regression parameters if the variance function ismisspecified.Τεκμήριο Estimation of age and gender food availability from household budget survey data(Athens University of Economics and Business, 05-2003) Karakou, Sofia K.; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Estimation using generalized estimating equations in complex repeated measures data: an application to periodontitis data(Athens University of Economics and Business, 03-2005) Athanasopoulou, Joanna E.; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Introducing meta-analysis methods for formulating, evaluating and combining information from medical studies(Athens University of Economics and Business, 07-2014) Antoniou, Nikoletta G.; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο A linear mixed effects application to data coming from patients suffering from periodontitis(Athens University of Economics and Business, 2006) Bakogeorgou, Maria Th.; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο A longitudinal data analysis using linear mixed effects models(Athens University of Economics and Business, 09-2003) Karamanlis, Orestis G.; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Meta-analysis of randomized controlled trials with zero events(22-06-2017) Tasouli, Foteini; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Meta-analysis is a statistical procedure for combining information from alreadyexisting studies. In the last thirty years, meta-analysis met a rapid increase in themedical world due to greater emphasis of evidence-based medicine and the need formore reliable findings. Most meta-analyses within the field of medical research havebeen conducted on clinical trials and especially on randomized controlled trials. De-spite the development of meta-analytic techniques, the meta-analysis of randomizedcontrolled trials with the occurrence of zero events is still a statistical challenge.The current thesis aims to introduce the general concept of meta-analysis andfocuses on meta-analysis of randomized controlled trials with the occurrence of zeroevents. After we review the basic ideas of meta-analysis, we will examine the classicmeta-analytic methods in the presence of zero events. Then, we will proceed tothe presentation of alternative approaches. A real dataset with zero events, whichinvestigates the risk for major adverse cardiovascular events in patients treated withanti-IL-12/23 biological agents for chronic plaque psoriasis will be used for analysis.The objective is to apply the methods under investigation to the real dataset andevaluate their behaviour. Afterwards, we will compare the performance of somemeta-analytic methods in a simulation study. Finally, the conclusions of this thesiswill be discussed.Τεκμήριο A pairwise likelihood estimation approach to an underline latent variable for ordinal responses(Athens University of Economics and Business, 12-2010) Rizopoulos, Charalampos K.; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Semiparametric generalized additive models: an application to periontitis data(Athens University of Economics and Business, 05-2004) Vareli, Aikaterini A.; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Tracing the rate of CD4-cell and viral load since initiation of antiretroviral treatment of HIV+ patient(Athens University of Economics and Business, 01-2003) Giannakopoulou, Judith G.; Athens University of Economics and Business, Department of Statistics; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Training courses and supportive services for socialy excluded groups(Athens University of Economics and Business, 11-2003) Chatzopoulos, Agisilaos A.; Vasdekis, V.Thesis - Athens University of Economics and Business. Postgraduate, Department of StatisticsΤεκμήριο Using a multinomial logit model to evaluate the demand for for pharmaceutical drugs in the Greek market(Athens University of Economics and Business, 06-2012) Λυκουρίνα, Άννα Ι.; Vasdekis, V.Διπλωματική εργασία - Οικονομικό Πανεπιστήμιο Αθηνών. ΜΠΣ, Τμήμα Στατιστικής (part-time)