• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 68
  • 10
  • 8
  • 6
  • 5
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 138
  • 47
  • 34
  • 29
  • 25
  • 23
  • 18
  • 18
  • 16
  • 15
  • 15
  • 13
  • 11
  • 10
  • 9
  • 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.
101

Variable Selection for High-Dimensional Data with Error Control

Fu, Han 23 September 2022 (has links)
No description available.
102

Examining The Association Between Transformational Leadership and Public Organizational Performance

Banee, Rabita Reshmeen 26 August 2022 (has links)
This dissertation examines the association between transformational leadership and public organizational performance using different data and methods. Each of the three articles collected in this dissertation contributes to the scholarship exploring the interplay of transformational leadership and organizational performance using distinct data and interpretive methods, examining the interplay of its elements and a widely used outcome measure – organizational performance as a dependent variable. The first article presents evidence of the empirical studies analyzing the association between transformational leadership and public organizational performance. Based on a formal, replicable search method informed by current practices for the systematic evaluation of published evidence, this review collects and analyzes empirical research articles examining the association between transformational leadership and public organizational performance. A total of seven journal articles were identified that met the study criteria. The measures of the transformational leadership construct in these studies are different but show a common pattern of survey questionnaires with multiple-level responses. Moreover, transformational leadership is found to be positively associated with public organizational performance. Organizational performance is operationalized using several factors such as development, growth, creativity, and effectiveness in the included studies. Acknowledging the gap in the included studies, this review offers two research questions for further exploration to address the gaps in the existing studies. The second article explores the association between the elements of transformational leadership and federal organizational performance in very large and large federal agencies using Ordinal Logistic Regression (OLR) on quantitative survey data drawn from results of the OPM Federal Employment Viewpoint Survey. Statistical findings of this study show a positive relationship between the elements of transformational leadership and organizational performance. This study contributes to the transformational leadership and public management literature by adding the scholarship exploring the association between the elements of transformational leadership and public organizational performance. The third article explores the association between transformational leadership and organizational performance from the experiences and perspectives of U.S. federal agency employees. The data was collected through semi-structured interviews with federal leaders from very large and large agencies, as per the Office of Personnel Management's classification. The perceptions of federal employees reflect the interplay between transformational leadership behaviors and perceptions of organizational performance. The informants' interviews enhance the understanding of transformational leadership-organizational performance association from the employee perspective. A process of thematic coding and interpretation is employed to analyze the interview data. The study findings contribute to the management and leadership literature by exploring the lived experiences of federal employees and their perceptions of the influence of transformational leadership on organizational performance. Moreover, the replicable qualitative interview process and analysis methodology create a pathway for future qualitative research. / Doctor of Philosophy / The influence of leadership is widely studied in terms of organizational performance. Among the leadership theories thought to influence organizational performance, transformational leadership is the most widely studied theory. The theory has gained much attention in the past 40 years for its contribution to many positive organizational outcomes, including meaningful work, organizational commitment, job satisfaction, and organizational performance. Despite a rich history of research in positive organizational outcomes, scholars still argue that there are scopes further to advance the empirical research on transformational leadership theory. Hence, the purpose of this dissertation is to address this claim and analyze the interplay between transformational leadership and public organizational performance. Study findings will contribute to the literature on transformational leadership by empirically examining the interplay of its elements and federal organizational performance. Moreover, the application of three distinct methods and interpretative data analysis will add new evidence to the research of public management and leadership.
103

Generació additiva de funcions d'agregació conjuntives i disjuntives discretes

Monreal Garcies, Jaume 14 September 2012 (has links)
En aquest treball es defineix el concepte de generador additiu de t–normes i de t–conormes discretes. S’hi estableixen resultats generals sobre la generació additiva de disjuncions i les caracteritzacions dels generadors de les t–conormes bàsiques. Es planteja un algorisme per a decidir quan una disjunció és additivament generable, basat en l’algorisme Gamma de la teoria de convexitat. S’estudia la relació que hi ha entre la generació additiva amb la suma ordinal i amb l’anidament. S’introdueixen els conceptes de generador concau i generador convex. S’estudia la generació additiva de les disjuncions i les t–conormes suaus i bivalents sobre L*. S’insisteix amb l’aplicabilitat de la generació additiva quan es tracta de manejar la condició de T–transitivitat per a relacions d’indistingibilitat discretes. Finalment, s’estudia la relació que hi ha entre la generació additiva d’una t–conorma S i les propietats de l’S–implicació corresponent. Amb motiu de les propietats d’ordre i modus ponens generalitzat, es defineixen els generadors mixtos
104

順序尺度資料間之相關性研究

廖俊嘉 Unknown Date (has links)
摘要 皮爾森相關係數通常作為描述區間尺度變數間相關性的參考指標,然而在社會科學領域中,由於資料多數以順序尺度的形式呈現,因此藉由傳統的皮爾森相關係數來描述順序尺度資料間的相關性通常會導致某種程度的誤差。儘管如此,以往的文獻多數傾向支持以等距離分數來取代順序尺度資料,並直接計算皮爾森相關係數。藉由模擬實驗的結果,我們發現這樣的作法並非在所有情況下都合理。 此外本研究中也對多序類相關係數進行探討。就表示順序變數間相關性的準確程度而言,多序類相關係數明顯優於利用等距離分數來計算皮爾森相關係數的方法;但若以操作上的便利程度而言,後者仍具有其優勢。 關鍵字:順序尺度、皮爾森相關係數、多序類相關係數。 / Abstract Pearson correlation coefficient is typically used to describe the correlation between two interval-scaled variables. In social science, however, most of the data are represented in ordinal-scale, and hence describing the correlation between two ordinal-scaled variables in terms of Pearson correlation coefficient would inevitably result in certain errors. Though the practice is deemed acceptable and generally supported in literatures, we found, through intensive simulations, that it should be executed with care. Polychoric correlation coefficient was also investigated. In order to describe the correlation between two ordinal-scaled variables, we found, in terms of the degree of accuracy, that Polychoric correlation coefficient is definitely better than Pearson correlation coefficient with equal-distance scores. Pearson correlation coefficient, on the other hands, is much easier to calculate, and should not be totally ignored. Key words:Ordinal-scale、Pearson correlation coefficient、Polychoric correlation coefficient。
105

Podmíněnosti spokojenosti se životem v Česku se zaměřením na geografické faktory / Determinants of life satisfaction in Czechia with the focus on geographical factors

Procházka, Petr January 2015 (has links)
The objective of this thesis is to analyse determinants of subjective well-being in Czechia and to compare them with other empirical evidence from Czechia and abroad. Main theoretical approaches include those emphasising "psychological" factors and those emphasising factors outside of the human personality. Data from the Public Opinion Research Centre of more than 2,000 respondents from Czechia of years 2013 and 2014 were analysed statistically. Measures of so-called global and local subjective well-being were dependent variables. Independent variables include "geographical" and demographic variables and other dummies. It was confirmed that people living in more populated buildings, with a lower space mobility, older, of a lower employment status or unemployed, lower education and left-wing oriented declare usually a lower results on the subjective well-being, too. Gender and income had variable effect on the subjective well-being. Theoretical assumptions were not confirmed considering the settlement size, mode of commuting and religion.
106

Use of data analysis techniques to solve specific bioinformatics problems / Apport de techniques d'analyse de données pour résoudre des problèmes spécifiques en bio-informatique

Moulin, Serge 12 December 2018 (has links)
De nos jours, la quantité de données génétiques séquencées augmente de manière exponentielle sous l'impulsion d'outils de séquençage de plus en plus performants, tels que les outils de séquençage haut débit en particulier. De plus, ces données sont de plus en plus facilement accessibles grâce aux bases de données en ligne. Cette plus grande disponibilité des données ouvre de nouveaux sujets d'étude qui nécessitent de la part des statisticiens et bio-informaticiens de développer des outils adaptés. Par ailleurs, les progrès constants de la statistique, dans des domaines tels que le clustering, la réduction de dimension, ou les régressions entre autres, nécessitent d'être régulièrement adaptés au contexte de la bio-informatique. L’objectif de cette thèse est l’application de techniques avancées de statistiques à des problématiques de bio-informatique. Dans ce manuscrit, nous présentons les résultats de nos travaux concernant le clustering de séquences génétiques via Laplacian eigenmaps et modèle de mélange gaussien, l'étude de la propagation des éléments transposables dans le génome via un processus de branchement, l'analyse de données métagénomiques en écologie via des courbes ROC ou encore la régression polytomique ordonnée pénalisée par la norme l1. / Nowadays, the quantity of sequenced genetic data is increasing exponentially under the impetus of increasingly powerful sequencing tools, such as high-throughput sequencing tools in particular. In addition, these data are increasingly accessible through online databases. This greater availability of data opens up new areas of study that require statisticians and bioinformaticians to develop appropriate tools. In addition, constant statistical progress in areas such as clustering, dimensionality reduction, regressions and others needs to be regularly adapted to the context of bioinformatics. The objective of this thesis is the application of advanced statistical techniques to bioinformatics issues. In this manuscript we present the results of our works concerning the clustering of genetic sequences via Laplacian eigenmaps and Gaussian mixture model, the study of the propagation of transposable elements in the genome via a branching process, the analysis of metagenomic data in ecology via ROC curves or the ordinal polytomous regression penalized by the l1-norm.
107

Χρήση μεθόδων πολυπαραγοντικής ανάλυσης (multifactor) για τον καθορισμό του ρίσκου του επενδυτικού σε δάνεια χαρτοφυλακίου των ελληνικών τραπεζών

Κωνσταντάρας, Κωνσταντίνος 19 August 2009 (has links)
Η έρευνά μας συμβάλει στην αντιμετώπιση του πιστοληπτικού κινδύνου της εισηγμένης σε ενιαία μορφή, συνυπολογιζομένης της μη-γραμμικής υποτιθέμενης σχέσης μεταξύ κινδύνου και χρηματιστηριακής αξίας της μετοχής, μιας και η ενδεχόμενη θέση της σε Επιτήρηση/Αναστολή αυξάνει δραματικά τις πιστοληπτικές επιπτώσεις στους πιστωτές, ιδιαίτερα σε όσους κατέχουν μετοχικό ενέχυρο, δημιουργώντας μια μη-γραμμική σχέση μεταξύ αξίας δανείων και αξίας μετοχής. Συνέπεια λοιπόν των επιταγών της Βασιλείας ΙΙ είναι και η κατηγοριοποίηση που διενεργούμε εμείς στο δείγμα των επιχειρήσεων που έχουν εισηγμένη μετοχή στο χρηματιστήριο, μιας και αναμένουμε να διαφοροποιείται ο κίνδυνος πτώχευσης και κίνδυνος από την έκθεση σε κίνδυνο και ζημιά από πτώχευση στην περίπτωση θέσης των μετοχών σε αναστολή ή Επιτήρηση. Πιστεύουμε ότι με αυτόν τον τρόπο συνεισφέρουμε στην εκτίμηση του κινδύνου που πηγάζει από την συστηματική αυτή εξάρτηση της εταιρίας και του πιστοληπτικού της κινδύνου από την έκθεση των μετοχών της στο χρηματιστήριο. / Our research contributes in the credit risk estimation for a listed company in an integrated framework, incorportating the assumed non-linear relationship between credit risk and stock-market performance deriving from a potential Stock Exchange trading Suspension/Supervision which modifies dramatically counterparty creditworthness and at the same time stock collateral held in a non-linear fashion. As a result of Basle II Accord's integrated credit risk estimation approach, we categorize the sample of listed enterprises according to their modified credit risk based on the potential Stock Exchange Supervision/Suspension. Our overall methodology of credit risk estimation stemming from a systematic dependence of credit and stock collateral risk contributes to the overall risk assesment of listed companies.
108

Ποιοτικός έλεγχος ραφής σε υπερ-εύκαμπτα υλικά με χρήση μεθόδων ψηφιακής επεξεργασίας σημάτων βίντεο / Seam quality control of non-rigid materials based on digital signal processing techniques of video data

Μαριόλης, Ιωάννης 07 July 2010 (has links)
Στα πλαίσια της διατριβής μελετήθηκε αρχικά το πρόβλημα της εύρεσης της θέσης του υφάσματος επάνω στην τράπεζα εργασίας με μεθόδους ψηφιακής ανάλυσης σημάτων βίντεο, παρουσία φαινομένων παραμόρφωσης και μερικής επικάλυψης του υφάσματος. Οι νέες μέθοδοι εντοπισμού που αναπτύχθηκαν αξιολογήθηκαν πειραματικά παρουσιάζοντας ικανοποιητική ακρίβεια εντοπισμού και ανοχή του συστήματος σε μερικές επικαλύψεις και παραμορφώσεις. Μετά την ολοκλήρωση της ραφής του υφάσματος πραγματοποιείται αυτόματος εντοπισμός της θέσης της ραφής από ψηφιακές φωτογραφίες. Αναπτύχθηκαν τρείς πρωτότυπες μέθοδοι εντοπισμού της θέσης της ραφής οι οποίες διαφοροποιούνται στο στάδιο της προεπεξεργασίας. Η πειραματική αξιολόγηση γίνεται σε βάση δεδομένων που περιέχει 118 εικόνες έτοιμων ενδυμάτων. Προτού πραγματοποιηθεί ποιοτικός έλεγχος ραφής, οι εικόνες κανονικοποιούνται ως προς τη θέση και τον προσανατολισμό της ραφής χρησιμοποιώντας τις παραπάνω μεθόδους αυτόματου εντοπισμού της θέσης της ραφής. Αναπτύχθηκαν και αξιολογήθηκαν τρείς διαφορετικές μέθοδοι αυτόματης αναγνώρισης της ποιότητας σε δείγματα ραφής οι οποίες εξάγουν τρία διαφορετικά σύνολα χαρακτηριστικών. Η πρώτη μέθοδος βασίζεται σε φασματικά χαρακτηριστικά, η δεύτερη στην επιβολή αυτό-σκίασης, ενώ η τρίτη βασίζεται στην εκτίμηση της ανομοιομορφίας της επιφάνειας των δειγμάτων ραφής. Η πειραματική αξιολόγηση γίνεται σε βάση δεδομένων δειγμάτων ραφής που περιλαμβάνει 325 ραφές. Η εκτίμηση της ποιότητας ραφής πραγματοποιείται με ταξινόμηση σε πέντε διατεταγμένους βαθμούς ποιότητας. Σε αυτήν την κατεύθυνση, προτείνονται και συγκρίνονται τέσσερις μέθοδοι αναγνώρισης προτύπων διατεταγμένων κατηγοριών. Η πρώτη μέθοδος χρησιμοποιεί για την ταξινόμηση μοντέλο σύμμετρων αναλογιών πιθανότητας. Η δεύτερη μέθοδος κάνει αναγνώριση με χρήση γραμμικού μοντέλου. Οι άλλες δύο μέθοδοι είναι πρωτότυπες και επίσης χρησιμοποιούν γραμμικό μοντέλο για την ταξινόμηση. Η διαφοροποίησή τους από τη δεύτερη μέθοδο είναι ότι η επιλογή των αριθμητικών τιμών των διατεταγμένων κατηγορίων δεν γίνεται αυθαίρετα., αλλά προκύπτει ως λύση προβλημάτων ελαχιστοποίησης.. Η πειραματική αξιολόγηση και σύγκριση των μεθόδων στο πρόβλημα του ποιοτικού ελέγχου ραφών οδηγεί στην επιλογή του μοντέλου σύμμετρων αναλογιών πιθανότητας σε περίπτωση που υπάρχει ικανός αριθμός παραδειγμάτων εκπαίδευσης, ενώ σε αντίθετη περίπτωση μπορεί να προτιμηθεί το γραμμικό μοντέλο αφού προηγηθεί βελτιστοποίηση με χρήση κάποιας εκ των δύο προτεινόμενων μεθόδων επιλογής αριθμητικών τιμών. / One of the problems studied in the present dissertation is that of the detection of the fabrics’ position on the working area. The proposed detection methods are based on image processing and analysis techniques and take into consideration both partial occlusion and fabric deformation. The methods have been experimentally evaluated and the results indicate sufficient detection accuracy and robustness regarding partial occlusion and fabric deformation. After sewing the fabric, the position and orientation of the seam is automatically detected. Three novel seam detection methods have been developed using different pre-processing techniques. The experimental evaluation of the three detection methods is made on a database containing 118 images of ready sewn garments. Before performing seam quality control the seam images are normalized with respect to the seam position and orientation, using the aforementioned seam detection methods. Feature selection has been studied next, extracting three different sets of features and assessing seam quality using three different methods. The first method uses spectral features; the second method is based on the detection of self-shadows onto the seam specimens, while the third method is based on the estimation of the surface roughness of the specimens. The experimental evaluation of the proposed methods is made on a database containing 325 images of seam specimens. Seam quality control is performed by classifying the seam specimens into five ordinal grades of quality. In this direction, four classification methods are proposed and evaluated, taking into account the ordered arrangement of the classes. The first method uses the proportional odds model; while the second method uses a linear model. The other two methods are novel and also employ a linear model. The difference between these two methods and the second method is that the numerical values they are assigning to the ordered categories are not arbitrary like in the case of the second method. The experimental evaluation of these four methods indicates that in case of a large number of training data, the first method which is based on the proportional odds model is more efficient, while in case of an insufficient number of training data the linear model optimized by one of the two novel methods should be selected.
109

Some properties of measures of disagreement and disorder in paired ordinal data

Högberg, Hans January 2010 (has links)
The measures studied in this thesis were a measure of disorder, D, and a measure of the individual part of the disagreement, the measure of relative rank variance, RV, proposed by Svensson in 1993. The measure of disorder is a useful measure of order consistency in paired assessments of scales with a different number of possible values. The measure of relative rank variance is a useful measure in evaluating reliability and for evaluating change in qualitative outcome variables. In Paper I an overview of methods used in the analysis of dependent ordinal data and a comparison of the methods regarding the assumptions, specifications, applicability, and implications for use were made. In Paper II an application, and a comparison of the results of some standard models, tests, and measures to two different research problems were made. The sampling distribution of the measure of disorder was studied both analytically and by a simulation experiment in Paper III. The asymptotic normal distribution was shown by the theory of U-statistics and the simulation experiments for finite sample sizes and various amount of disorder showed that the sampling distribution was approximately normal for sample sizes of about 40 to 60 for moderate sizes of D and for smaller sample sizes for substantial sizes of D. The sampling distribution of the relative rank variance was studied in a simulation experiment in Paper IV. The simulation experiment showed that the sampling distribution was approximately normal for sample sizes of 60-100 for moderate size of RV, and for smaller sample sizes for substantial size of RV. In Paper V a procedure for inference regarding relative rank variances from two or more samples was proposed. Pair-wise comparison by jackknife technique for variance estimation and the use of normal distribution as approximation in inference for parameters in independent samples based on the results in Paper IV were demonstrated. Moreover, an application of Kruskal-Wallis test for independent samples and Friedman’s test for dependent samples were conducted. / Statistical methods for ordinal data
110

Die statistische Auswertung von ordinalen Daten bei zwei Zeitpunkten und zwei Stichproben / The Statistical Analysis of Ordinal Data at two Timepoints and two Groups

Siemer, Alexander 03 April 2002 (has links)
No description available.

Page generated in 0.0409 seconds