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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Asymptotische Äquivalenz für ein Modell unabhängiger nicht identisch verteilter Daten

Jähnisch, Michael. January 1999 (has links)
Berlin, Humboldt-Universiẗat, Diss., 1999.
2

Some issues of teaching statistical thinking

Krauss, Stefan. January 2003 (has links)
Berlin, Freie University, Diss., 2001. / Dateiformat: zip, Dateien im PDF-Format.
3

Entwicklung, Einsatz und Evaluation multimedialer Lernsoftware in der Statistikausbildung

Pabst, Alexandra. January 2004 (has links) (PDF)
Bielefeld, Universiẗat, Diss., 2004.
4

Statistical models and likelihood ratio proesses for interacting particle systems with branching and immigration /

Löcherbach, Eva. January 1999 (has links)
University-GH, Diss.--Paderborn, 1999.
5

Essays on Model Assisted Survey Planning

Holmberg, Anders January 2003 (has links)
The quality of sample survey results is to a large degree dependent on decisions made by survey statisticians at the planning stage. The first paper studies two issues related to the planning stage: (i) the sensitivity of model assumptions concerning the relation between the size measure and a study variable in without replacement probability proportional-to-size sampling (πps sampling), and (ii) properties of practicable sample selection schemes for fixed size πps sampling. These two issues are also addressed in the second paper, which furthermore discusses the consequences of the presence of more than one study variable and to what extent the auxiliary information used in the design and that used in the estimators interact. The evident problem in both the first and the second paper is how to choose an overall efficient sampling design when there are several important study variables with various relationships to the available auxiliary variables. The third paper suggests a diagnostic tool to support the choice of design, and on the basis of three criteria of overall efficiency optimal designs are derived. The optimal designs presented in the third paper may not be fully satisfactory in meeting specified precision requirements for separate estimators. To achieve a design that is tailor-made to meet such requirements, optimisation must be done under restrictions. Though the underlying optimisation problem is only outlined in paper III, a solution involving non-linear programming methods is given in the fourth paper. By way of an example based on an application to a Swedish business population, the fourth paper compares a design obtained through non-linear programming algorithms with designs discussed in paper III as well as designs based on the same principal ideas as those discussed in the first two papers. The paper suggests a flexible solution regarding how to use auxiliary information exhaustively and to provide diagnostic support for the final design choice.
6

Essays on Model Assisted Survey Planning

Holmberg, Anders January 2003 (has links)
<p>The quality of sample survey results is to a large degree dependent on decisions made by survey statisticians at the planning stage. The first paper studies two issues related to the planning stage: (i) the sensitivity of model assumptions concerning the relation between the size measure and a study variable in without replacement probability proportional-to-size sampling (π<i>p</i>s sampling), and (ii) properties of practicable sample selection schemes for fixed size π<i>p</i>s sampling. These two issues are also addressed in the second paper, which furthermore discusses the consequences of the presence of more than one study variable and to what extent the auxiliary information used in the design and that used in the estimators interact.</p><p>The evident problem in both the first and the second paper is how to choose an overall efficient sampling design when there are several important study variables with various relationships to the available auxiliary variables. The third paper suggests a diagnostic tool to support the choice of design, and on the basis of three criteria of overall efficiency optimal designs are derived.</p><p>The optimal designs presented in the third paper may not be fully satisfactory in meeting specified precision requirements for separate estimators. To achieve a design that is tailor-made to meet such requirements, optimisation must be done under restrictions. Though the underlying optimisation problem is only outlined in paper III, a solution involving non-linear programming methods is given in the fourth paper. By way of an example based on an application to a Swedish business population, the fourth paper compares a design obtained through non-linear programming algorithms with designs discussed in paper III as well as designs based on the same principal ideas as those discussed in the first two papers. The paper suggests a flexible solution regarding how to use auxiliary information exhaustively and to provide diagnostic support for the final design choice.</p>
7

Schätzer des Artenreichtums bei speziellen Erscheinungshäufigkeiten / Species richness estimation

Englert, Stefan January 2009 (has links) (PDF)
Bei vielen Fragestellungen, in denen sich eine Grundgesamtheit in verschiedene Klassen unterteilt, ist weniger die relative Klassengröße als vielmehr die Anzahl der Klassen von Bedeutung. So interessiert sich beispielsweise der Biologe dafür, wie viele Spezien einer Gattung es gibt, der Numismatiker dafür, wie viele Münzen oder Münzprägestätten es in einer Epoche gab, der Informatiker dafür, wie viele unterschiedlichen Einträge es in einer sehr großen Datenbank gibt, der Programmierer dafür, wie viele Fehler eine Software enthält oder der Germanist dafür, wie groß der Wortschatz eines Autors war oder ist. Dieser Artenreichtum ist die einfachste und intuitivste Art und Weise eine Population oder Grundgesamtheit zu charakterisieren. Jedoch kann nur in Kollektiven, in denen die Gesamtanzahl der Bestandteile bekannt und relativ klein ist, die Anzahl der verschiedenen Spezien durch Erfassung aller bestimmt werden. In allen anderen Fällen ist es notwendig die Spezienanzahl durch Schätzungen zu bestimmen.
8

USING FINITE MIXTURE OF MULTIVARIATE POISSON FOR DETECTION OF MEASUREMENT ERRORS IN COUNT DATA

Rota, Bernardo Joao January 2010 (has links)
No description available.
9

AN EMPIRICAL STUDY OF YOUTHS AND CRIME

Landare, Nora, Dalesjö, Hanna January 2015 (has links)
Criminality can have serious and numerous effects of both individuals and society and why youths engage in criminal actions is a question concerning several instances. In this study we investigate possible factors that influence criminality among youths by analyzing a self-survey questionnaire. To identify the factors the technique of exploratory factor analysis is used. The relationships between the factors and criminality are then assessed with a structural equation model. The objective is also to investigate if the factors relate differently to criminality depending on gender why the structural equation model is performed on males and females separately. From the analysis we identified seven factors. Four of them seem to have an impact on youths’ criminal behavior; criminality among friends, attitudes towards severe crimes, relationships to friends and exposure and participation in negative social behavior. For the other three factors (school performance, family relations and attitude towards illicit actions) we found no clear relationship to criminal behavior. The results also indicate that criminality among friends influence males to a larger degree than females. Whereas the relationship between criminal behavior and exposure and participation in negative social behavior is stronger for females than males. For the other factors no major differences between male and females can be distinguished. The overall picture produced by the analysis suggest that the influences of the identified factors on criminality are quite modest and that the patterns for males and females are quite similar.
10

Contributions to the Theory of Measures of Association for Ordinal Variables

Ekström, Joakim January 2009 (has links)
In this thesis, we consider measures of association for ordinal variables from a theoretical perspective. In particular, we study the phi-coefficient, the tetrachoric correlation coefficient and the polychoric correlation coefficient. We also introduce a new measure of association for ordinal variables, the empirical polychoric correlation coefficient, which has better theoretical properties than the polychoric correlation coefficient, including greatly enhanced robustness. In the first article, entitled ``On the relation between the phi-coefficient and the tetrachoric correlation coefficient'', we show that under given marginal probabilities there exists a continuous bijection between the two measures of association. Furthermore, we show that the bijection has a fixed point at zero for all marginal probabilities. Consequently, the choice of which of these measures of association to use is for all practical purposes a matter of preference only. In the second article, entitled ``A generalized definition of the tetrachoric correlation coefficient'', we generalize the tetrachoric correlation coefficient so that a large class of parametric families of bivariate distributions can be assumed as underlying distributions. We also provide a necessary and sufficient condition for the generalized tetrachoric correlation coefficient to be well defined for a given parametric family of bivariate distributions. With examples, we illustrate the effects on the polychoric correlation coefficient of different distributional assumptions. In the third article, entitled ``A generalized definition of the polychoric correlation coefficient'', we generalize the polychoric correlation coefficient to a large class of parametric families of bivariate distributions, and show that the generalized and the conventional polychoric correlation coefficients agree on the family of bivariate normal distributions. With examples, we illustrate the effects of different distributional assumptions on the polychoric correlation coefficient. In combination with goodness-of-fit p-values, the association analysis can be enriched with a consideration of possible tail dependence. In the fourth article, we propose a new measure of association for ordinal variables, named the empirical polychoric correlation coefficient. The empirical polychoric correlation coefficient relaxes the fundamental assumption of the polychoric correlation coefficient so that an underlying joint distribution is only assumed to exist, not to be of a particular parametric family. We also provide an asymptotical result, by which the empirical polychoric correlation coefficient converges almost surely to the true polychoric correlation under very general conditions. Thus, the proposed empirical polychoric correlation coefficient has better theoretical properties than the polychoric correlation coefficient.

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