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Confidence bands in quantile regression and generalized dynamic semiparametric factor modelsSong, Song 01 November 2010 (has links)
In vielen Anwendungen ist es notwendig, die stochastische Schwankungen der maximalen Abweichungen der nichtparametrischen Schätzer von Quantil zu wissen, zB um die verschiedene parametrische Modelle zu überprüfen. Einheitliche Konfidenzbänder sind daher für nichtparametrische Quantil Schätzungen der Regressionsfunktionen gebaut. Die erste Methode basiert auf der starken Approximation der empirischen Verfahren und Extremwert-Theorie. Die starke gleichmäßige Konsistenz liegt auch unter allgemeinen Bedingungen etabliert. Die zweite Methode beruht auf der Bootstrap Resampling-Verfahren. Es ist bewiesen, dass die Bootstrap-Approximation eine wesentliche Verbesserung ergibt. Der Fall von mehrdimensionalen und diskrete Regressorvariablen wird mit Hilfe einer partiellen linearen Modell behandelt. Das Verfahren wird mithilfe der Arbeitsmarktanalysebeispiel erklärt. Hoch-dimensionale Zeitreihen, die nichtstationäre und eventuell periodische Verhalten zeigen, sind häufig in vielen Bereichen der Wissenschaft, zB Makroökonomie, Meteorologie, Medizin und Financial Engineering, getroffen. Der typische Modelierungsansatz ist die Modellierung von hochdimensionalen Zeitreihen in Zeit Ausbreitung der niedrig dimensionalen Zeitreihen und hoch-dimensionale zeitinvarianten Funktionen über dynamische Faktorenanalyse zu teilen. Wir schlagen ein zweistufiges Schätzverfahren. Im ersten Schritt entfernen wir den Langzeittrend der Zeitreihen durch Einbeziehung Zeitbasis von der Gruppe Lasso-Technik und wählen den Raumbasis mithilfe der funktionalen Hauptkomponentenanalyse aus. Wir zeigen die Eigenschaften dieser Schätzer unter den abhängigen Szenario. Im zweiten Schritt erhalten wir den trendbereinigten niedrig-dimensionalen stochastischen Prozess (stationär). / In many applications it is necessary to know the stochastic fluctuation of the maximal deviations of the nonparametric quantile estimates, e.g. for various parametric models check. Uniform confidence bands are therefore constructed for nonparametric quantile estimates of regression functions. The first method is based on the strong approximations of the empirical process and extreme value theory. The strong uniform consistency rate is also established under general conditions. The second method is based on the bootstrap resampling method. It is proved that the bootstrap approximation provides a substantial improvement. The case of multidimensional and discrete regressor variables is dealt with using a partial linear model. A labor market analysis is provided to illustrate the method. High dimensional time series which reveal nonstationary and possibly periodic behavior occur frequently in many fields of science, e.g. macroeconomics, meteorology, medicine and financial engineering. One of the common approach is to separate the modeling of high dimensional time series to time propagation of low dimensional time series and high dimensional time invariant functions via dynamic factor analysis. We propose a two-step estimation procedure. At the first step, we detrend the time series by incorporating time basis selected by the group Lasso-type technique and choose the space basis based on smoothed functional principal component analysis. We show properties of this estimator under the dependent scenario. At the second step, we obtain the detrended low dimensional stochastic process (stationary).
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[pt] ESTIMAÇÕES NÃO PARAMÉTRICAS DE CURVAS DE JUROS: CRITÉRIO DE SELEÇÃO DE MODELO, FATORES DETERMINANTES DEDESEMPENHO E BID-ASK SPREAD / [en] NON-PARAMETRIC ESTIMATIONS OF INTEREST RATE CURVES : MODEL SELECTION CRITERION: MODEL SELECTION CRITERIONPERFORMANCE DETERMINANT FACTORS AND BID-ASK SANDRE MONTEIRO D ALMEIDA MONTEIRO 11 June 2002 (has links)
[pt] Esta tese investiga a estimação de curvas de juros sob o
ponto de vista de métodos não-paramétricos. O texto está
dividido em dois blocos. O primeiro investiga a questão do
critério utilizado para selecionar o método de melhor
desempenho na tarefa de interpolar a curva de juros
brasileira em uma dada amostra. Foi proposto um critério
de
seleção de método baseado em estratégias de re-amostragem
do tipo leave-k-out cross validation, onde K k £ £ 1
e K é função do número de contratos observados a cada
curva
da amostra. Especificidades do problema reduzem o esforço
computacional requerido, tornando o critério factível. A
amostra tem freqüência diária: janeiro de 1997 a
fevereiro
de 2001. O critério proposto apontou o spline cúbico
natural -utilizado com método de ajuste perfeito aos
dados - como o método de melhor desempenho. Considerando
a
precisão de negociação, este spline mostrou-se não
viesado. A análise quantitativa de seu desempenho
identificou, contudo, heterocedasticidades nos erros
simulados. A partir da especificação da variância
condicional destes erros e de algumas hipóteses, foi
proposto um esquema de intervalo de segurança para a
estimação de taxas de juros pelo spline cúbico natural,
empregado como método de ajuste perfeito aos
dados. O backtest sugere que o esquema proposto é
consistente, acomodando bem as hipóteses e aproximações
envolvidas. O segundo bloco investiga a estimação da
curva
de juros norte-americana construída a partir dos
contratos
de swaps de taxas de juros dólar-Libor pela Máquina de
Vetores Suporte (MVS), parte do corpo da Teoria do
Aprendizado Estatístico. A pesquisa em MVS tem obtido
importantes avanços teóricos, embora ainda sejam escassas
as implementações em problemas reais de regressão. A MVS
possui características atrativas para a modelagem de
curva
de juros: é capaz de introduzir já na estimação
informações
a priori sobre o formato da curva e sobre aspectos da
formação das taxas e liquidez de cada um dos contratos a
partir dos quais ela é construída. Estas últimas são
quantificadas pelo bid-ask spread (BAS) de cada contrato.
A formulação básica da MVS é alterada para assimilar
diferentes valores do BAS sem que as propriedades dela
sejam perdidas. É dada especial atenção ao levantamento
de
informação a priori para seleção dos parâmetros da MVS a
partir do formato típico da curva. A amostra tem
freqüência diária: março de 1997 a abril de 2001. Os
desempenhos fora da amostra de diversas especificações da
MVS foram confrontados com aqueles de outros métodos de
estimação. A MVS foi o método que melhor controlou o
trade-
off entre viés e variância dos erros. / [en] This thesis investigates interest rates curve estimation
under non-parametric approach. The text is divided into two
parts. The first one focus on which criterion to use to
select the best performance method in the task of
interpolating Brazilian interest rate curve. A selection
criterion is proposed to measure out-of-sample performance
by combining resample strategies leave-k-out cross
validation applied upon the whole sample curves, where K k
£ £ 1 and K is function of observed contract number in each
curve. Some particularities reduce substantially
the required computational effort, making the proposed
criterion feasible. The data sample range is daily, from
January 1997 to February 2001. The proposed criterion
selected natural cubic spline, used as data perfect-fitting
estimation method. Considering the trade rate
precision, the spline is non-biased. However, quantitative
analysis of performance determinant factors showed the
existence of out-of-sample error heteroskedasticities. From
a conditional variance specification of these errors,
a security interval scheme is proposed for
interest rate generated by perfect-fitting natural cubic
spline. A backtest showed that the proposed security
interval is consistent, accommodating the evolved
assumptions and approximations.
The second part estimate US free-for-floating interest rate
swap contract curve by using Support Vector Machine (SVM),
a method derived from Statistical Learning Theory.
The SVM research has got important theoretical results,
however the number of implementation on real regression
problems is low. SVM has some attractive characteristics
for interest rates curves modeling: it has the ability to
introduce already in its estimation process a priori
information about curve shape and about liquidity and price
formation aspects of the contracts that generate the curve.
The last information set is quantified by the bid-ask
spread. The basic SVM formulation is changed in order to be
able to incorporate the different values for bid-ask
spreads, without losing its properties. Great attention is
given to the question of how to extract a priori
information from swap curve typical shape to be used in
MVS parameter selection. The data sample range is daily,
from March 1997 to April 2001.
The out-of-sample performances of different SVM
specifications are faced with others
method performances. SVM got the better control of trade-
off between bias and variance of out-of-sample errors.
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Bayes Filters with Improved Measurements for Visual Object Tracking / Bayes Filter mit verbesserter Messung für das Tracken visueller ObjekteLiu, Guoliang 20 March 2012 (has links)
No description available.
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Contribution à la statistique spatiale et l'analyse de données fonctionnelles / Contribution to spatial statistics and functional data analysisAhmed, Mohamed Salem 12 December 2017 (has links)
Ce mémoire de thèse porte sur la statistique inférentielle des données spatiales et/ou fonctionnelles. En effet, nous nous sommes intéressés à l’estimation de paramètres inconnus de certains modèles à partir d’échantillons obtenus par un processus d’échantillonnage aléatoire ou non (stratifié), composés de variables indépendantes ou spatialement dépendantes.La spécificité des méthodes proposées réside dans le fait qu’elles tiennent compte de la nature de l’échantillon étudié (échantillon stratifié ou composé de données spatiales dépendantes).Tout d’abord, nous étudions des données à valeurs dans un espace de dimension infinie ou dites ”données fonctionnelles”. Dans un premier temps, nous étudions les modèles de choix binaires fonctionnels dans un contexte d’échantillonnage par stratification endogène (échantillonnage Cas-Témoin ou échantillonnage basé sur le choix). La spécificité de cette étude réside sur le fait que la méthode proposée prend en considération le schéma d’échantillonnage. Nous décrivons une fonction de vraisemblance conditionnelle sous l’échantillonnage considérée et une stratégie de réduction de dimension afin d’introduire une estimation du modèle par vraisemblance conditionnelle. Nous étudions les propriétés asymptotiques des estimateurs proposées ainsi que leurs applications à des données simulées et réelles. Nous nous sommes ensuite intéressés à un modèle linéaire fonctionnel spatial auto-régressif. La particularité du modèle réside dans la nature fonctionnelle de la variable explicative et la structure de la dépendance spatiale des variables de l’échantillon considéré. La procédure d’estimation que nous proposons consiste à réduire la dimension infinie de la variable explicative fonctionnelle et à maximiser une quasi-vraisemblance associée au modèle. Nous établissons la consistance, la normalité asymptotique et les performances numériques des estimateurs proposés.Dans la deuxième partie du mémoire, nous abordons des problèmes de régression et prédiction de variables dépendantes à valeurs réelles. Nous commençons par généraliser la méthode de k-plus proches voisins (k-nearest neighbors; k-NN) afin de prédire un processus spatial en des sites non-observés, en présence de co-variables spatiaux. La spécificité du prédicteur proposé est qu’il tient compte d’une hétérogénéité au niveau de la co-variable utilisée. Nous établissons la convergence presque complète avec vitesse du prédicteur et donnons des résultats numériques à l’aide de données simulées et environnementales.Nous généralisons ensuite le modèle probit partiellement linéaire pour données indépendantes à des données spatiales. Nous utilisons un processus spatial linéaire pour modéliser les perturbations du processus considéré, permettant ainsi plus de flexibilité et d’englober plusieurs types de dépendances spatiales. Nous proposons une approche d’estimation semi paramétrique basée sur une vraisemblance pondérée et la méthode des moments généralisées et en étudions les propriétés asymptotiques et performances numériques. Une étude sur la détection des facteurs de risque de cancer VADS (voies aéro-digestives supérieures)dans la région Nord de France à l’aide de modèles spatiaux à choix binaire termine notre contribution. / This thesis is about statistical inference for spatial and/or functional data. Indeed, weare interested in estimation of unknown parameters of some models from random or nonrandom(stratified) samples composed of independent or spatially dependent variables.The specificity of the proposed methods lies in the fact that they take into considerationthe considered sample nature (stratified or spatial sample).We begin by studying data valued in a space of infinite dimension or so-called ”functionaldata”. First, we study a functional binary choice model explored in a case-controlor choice-based sample design context. The specificity of this study is that the proposedmethod takes into account the sampling scheme. We describe a conditional likelihoodfunction under the sampling distribution and a reduction of dimension strategy to definea feasible conditional maximum likelihood estimator of the model. Asymptotic propertiesof the proposed estimates as well as their application to simulated and real data are given.Secondly, we explore a functional linear autoregressive spatial model whose particularityis on the functional nature of the explanatory variable and the structure of the spatialdependence. The estimation procedure consists of reducing the infinite dimension of thefunctional variable and maximizing a quasi-likelihood function. We establish the consistencyand asymptotic normality of the estimator. The usefulness of the methodology isillustrated via simulations and an application to some real data.In the second part of the thesis, we address some estimation and prediction problemsof real random spatial variables. We start by generalizing the k-nearest neighbors method,namely k-NN, to predict a spatial process at non-observed locations using some covariates.The specificity of the proposed k-NN predictor lies in the fact that it is flexible and allowsa number of heterogeneity in the covariate. We establish the almost complete convergencewith rates of the spatial predictor whose performance is ensured by an application oversimulated and environmental data. In addition, we generalize the partially linear probitmodel of independent data to the spatial case. We use a linear process for disturbancesallowing various spatial dependencies and propose a semiparametric estimation approachbased on weighted likelihood and generalized method of moments methods. We establishthe consistency and asymptotic distribution of the proposed estimators and investigate thefinite sample performance of the estimators on simulated data. We end by an applicationof spatial binary choice models to identify UADT (Upper aerodigestive tract) cancer riskfactors in the north region of France which displays the highest rates of such cancerincidence and mortality of the country.
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