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Expectile regression
Ondřej, Josef ; Komárek, Arnošt (advisor) ; Pešta, Michal (referee)
In this thesis we present an alternative to quantiles, which is known as expectiles. At first we define the notion of expectile of a distribution of ran- dom variable and then we show some of its basic properties such as linearity or monotonic behavior of τ-th expectile eτ in τ. Let (Y, X), Y ∈ R, X ∈ Rp be a ran- dom vector. We define conditional expectile of Y given X = x, which we denote eτ (Y |X = x). We introduce model of expectile regression eτ (Y |X = x) = x⊤ βτ , where βτ ∈ Rp and we examine asymptotic behavior of estimate of the regression coefficients βτ and ways how to calculate it. Further we introduce semiparametric expectile regression, which generalizes the previous case and adds restrictions on the estimate of the regression coefficients which enforce desired properties such as smoothness of fitted curves. We illustrate the use of theoretical results on me- chanographic data, which describe dependence of power and force of a jump on age of children and adolescents aged between 6 and 18. Keywords: expectiles, expectile regression, quantiles, penalized B-splines 1
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Expectile regression
Ondřej, Josef ; Komárek, Arnošt (advisor) ; Pešta, Michal (referee)
In this thesis we present an alternative to quantiles, which is known as expectiles. At first we define the notion of expectile of a distribution of ran- dom variable and then we show some of its basic properties such as linearity or monotonic behavior of τ-th expectile eτ in τ. Let (Y, X), Y ∈ R, X ∈ Rp be a ran- dom vector. We define conditional expectile of Y given X = x, which we denote eτ (Y |X = x). We introduce model of expectile regression eτ (Y |X = x) = x⊤ βτ , where βτ ∈ Rp and we examine asymptotic behavior of estimate of the regression coefficients βτ and ways how to calculate it. Further we introduce semiparametric expectile regression, which generalizes the previous case and adds restrictions on the estimate of the regression coefficients which enforce desired properties such as smoothness of fitted curves. We illustrate the use of theoretical results on me- chanographic data, which describe dependence of power and force of a jump on age of children and adolescents aged between 6 and 18. Keywords: expectiles, expectile regression, quantiles, penalized B-splines 1
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Probability distributions on metric groups.
Ondřej, Josef ; Štěpán, Josef (advisor) ; Dostál, Petr (referee)
Title: Probability distributions on metric groups Author: Josef Ondřej Department: Department of Probability and Mathematical Statistics Supervisor: prof. RNDr. Josef Štěpán, DrSc., Department of Probability and Mathematical Statistics Abstract: In this thesis we deal with the space of Borel probability measures at first on a metric space and later on a metric group. We define the notion of a weak convergence of Borel probability measures and in a special case we show this convergence is metrizable. Further we introduce operation of convolution of Borel probability measures on a metric group and we show that together with this operation the space of measures becomes a topological semigroup. We use the notion of convolution to define idempotent and Haar measure and we show a relation between them. Finally we use the mentioned results to describe all solutions of Choquet problem. At the end we demonstrate how the theory that we have developed applies to a group of complex units. Keywords: Metric group, weak convergence, Prokhorov's theorem, Choquet's theorem.
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