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Tytuł:
Non-central generalized F distributions
Autorzy:
Nunes, Célia
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729690.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
exact distributions
random non-centrality parameters
generalized F distributions
Opis:
The quotient of two linear combinations of independent chi-squares will have a generalized F distribution. Exact expressions for these distributions when the chi-square are central and those in the numerator or in the denominator have even degrees of freedom were given in Fonseca et al. (2002). These expressions are now extended for non-central chi-squares. The case of random non-centrality parameters is also considered.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2006, 26, 1; 47-61
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selective F tests for sub-normal models
Autorzy:
Nunes, Célia
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729820.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
ective F tests
sub-normal models
max-min tests
orderings
Opis:
F tests that are specially powerful for selected alternatives are built for sub-normal models. In these models the observation vector is the sum of a vector that stands for what is measured with a normal error vector, both vectors being independent. The results now presented generalize the treatment given by Dias (1994) for normal fixed-effects models, and consider the testing of hypothesis on the ordering of mean values and components.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2003, 23, 2; 167-174
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stochastic vortices in periodically reclassified populations
Autorzy:
Guerreiro, Gracinda
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729714.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Markov chains
stochastic vortices
Opis:
Our paper considers open populations with arrivals and departures whose elements are subject to periodic reclassifications. These populations will be divided into a finite number of sub-populations.
Assuming that:
a) entries, reclassifications and departures occur at the beginning of the time units;
b) elements are reallocated at equally spaced times;
c) numbers of new elements entering at the beginning of the time units are realizations of independent Poisson distributed random variables;
we use Markov chains to obtain limit results for the relative sizes of the sub-populations corresponding to the states of the chain. Namely we will obtain conditions for stability of the relative sizes for transient and recurrent states as well as for all states. The existence of such stability corresponds to the existence of a stochastic structure based either on the transient or on the recurrent states or even on all states. We call these structures stochastic vortices because the structure is maintained despite entrances, departures and reallocations.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2008, 28, 2; 209-227
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An alternative approach to bonus malus
Autorzy:
Guerreiro, Gracinda
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729776.pdf
Data publikacji:
2004
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
bonus malus
stochastic vortices
long run distribution
optimal bonus scales
Opis:
Under the assumptions of an open portfolio, i.e., considering that a policyholder can transfer his policy to another insurance company and the continuous arrival of new policyholders into a portfolio which can be placed into any of the bonus classes and not only in the "starting class", we developed a model (Stochastic Vortices Model) to estimate the Long Run Distribution for a Bonus Malus System. These hypothesis render the model quite representative of the reality.
With the obtained Long Run Distribution, a few optimal bonus scales were calculated, such as Norberg's (1979), Borgan, Hoem's and Norberg's (1981), Gilde and Sundt's (1989) and Andrade e Silva's (1991).
To compare our results, since this was the first application of the model, we used the Classic Model for Bonus Malus and the Open Model developed by Centeno and Andrade e Silva (2001).
The results of the Stochastic Vortices and the Open Modelare highly similar and quite different from those of the Classic Model. Besides this the distribution of policyholders in the various bonus classes was derived assuming that the entrances followed adequatestochastic models.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2004, 24, 2; 197-213
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
F-tests for generalized linear hypotheses in subnormal models
Autorzy:
Mexia, Joao
Dias, Gerberto
Powiązania:
https://bibliotekanauki.pl/articles/729870.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
F-tests
subnormal models
mixed models
invariance
UMP tests
third type error
Opis:
When the measurement errors may be assumed to be normal and independent from what is measured a subnormal model may be used. We define a linear and generalized linear hypotheses for these models, and derive F-tests for them. These tests are shown to be UMP for linear hypotheses as well as strictly unbiased and strongly consistent for these hypotheses. It is also shown that the F-tests are invariant for regular transformations, possess structural stability and are almost strongly consistent for generalized linear hypothesis. An application to a mixed model studied by Michalskyi and Zmyślony is shown.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2001, 21, 1; 49-62
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strong law of large numbers for additive extremum estimators
Autorzy:
Mexia, João
Real, Pedro
Powiązania:
https://bibliotekanauki.pl/articles/729890.pdf
Data publikacji:
2001
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Kolmogorov's strong law of large numbers
multiple regression
almost sure convergence
additive extremum estimators
Opis:
Extremum estimators are obtained by maximizing or minimizing a function of the sample and of the parameters relatively to the parameters. When the function to maximize or minimize is the sum of subfunctions each depending on one observation, the extremum estimators are additive. Maximum likelihood estimators are extremum additive whenever the observations are independent. Another instance of additive extremum estimators are the least squares estimators for multiple regressions when the usual assumptions hold. A strong law of large numbers is derived for additive extremum estimators. This law requires only the existence of first order moments and may be of interest in connection with maximum likelihood estimators, since the usual assumption that the observations are identically distributed is discarded.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2001, 21, 2; 81-88
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Likelihood and parametric heteroscedasticity in normal connected linear models
Autorzy:
Mexia, Joao
Real, Pedro
Powiązania:
https://bibliotekanauki.pl/articles/729942.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
linear model
connected model
normal model
maximum likelihood estimators
score function
Newton-Raphson method
Opis:
A linear model in which the mean vector and covariance matrix depend on the same parameters is connected. Limit results for these models are presented. The characteristic function of the gradient of the score is obtained for normal connected models, thus, enabling the study of maximum likelihood estimators. A special case with diagonal covariance matrix is studied.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2000, 20, 2; 177-188
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ANOVA using commutative Jordan algebras, an application
Autorzy:
Rodrigues, Paulo
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729984.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
commutative Jordan algebras
variance components
orthogonal models
ANOVA
Opis:
Binary operations on commutative Jordan algebras are used to carry out the ANOVA of a two layer model. The treatments in the first layer nests those in the second layer, that being a sub-model for each treatment in the first layer. We present an application with data retried from agricultural experiments.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2006, 26, 2; 179-191
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Least squares estimator consistency: a geometric approach
Autorzy:
Mexia, João
da Silva, João
Powiązania:
https://bibliotekanauki.pl/articles/729688.pdf
Data publikacji:
2006
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
linear models
least squares estimator
consistency
radial symmetry
generalized polar coordinates
Opis:
Consistency of LSE estimator in linear models is studied assuming that the error vector has radial symmetry. Generalized polar coordinates and algebraic assumptions on the design matrix are considered in the results that are established.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2006, 26, 1; 19-45
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compact hypothesis and extremal set estimators
Autorzy:
Mexia, João
Corte Real, Pedro
Powiązania:
https://bibliotekanauki.pl/articles/729790.pdf
Data publikacji:
2003
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
extremal estimators
set estimators
confidence ellipsoids
strong consistency
binary data
Opis:
In extremal estimation theory the estimators are local or absolute extremes of functions defined on the cartesian product of the parameter by the sample space. Assuming that these functions converge uniformly, in a convenient stochastic way, to a limit function g, set estimators for the set ∇ of absolute maxima (minima) of g are obtained under the compactness assumption that ∇ is contained in a known compact U. A strongly consistent test is presented for this assumption. Moreover, when the true parameter value $\vec{β₀}^{k}$ is the sole point in ∇, strongly consistent pointwise estimators, ${ \^{\vec{βₙ}}^{k}: n ∈ ℕ }$ for $\vec{β₀}^{k}$ are derived and confidence ellipsoids for $\vec{β₀}^{k}$ centered at $\^{\vec{βₙ}}^{k}$ are obtained, as well as, strongly consistent tests. Lastly an application to binary data is presented.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2003, 23, 2; 103-121
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sufficient conditions for the strong consistency of least squares estimator with α-stable errors
Autorzy:
Mexia, João
da Silva, João
Powiązania:
https://bibliotekanauki.pl/articles/729990.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
linear models
least squares estimator
strong consistency
stability
Opis:
Let $Y_{i} = x_{i}^{T}β + e_{i}$, 1 ≤ i ≤ n, n ≥ 1 be a linear regression model and suppose that the random errors e₁, e₂, ... are independent and α-stable. In this paper, we obtain sufficient conditions for the strong consistency of the least squares estimator β̃ of β under additional assumptions on the non-random sequence x₁, x₂,... of real vectors.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2007, 27, 1-2; 27-45
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generalized F tests and selective generalized F tests for orthogonal and associated mixed models
Autorzy:
Nunes, Célia
Pinto, Iola
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729658.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
selective generalized F tests
generalized polar coordinates
associated models
Opis:
The statistics of generalized F tests are quotients of linear combinations of independent chi-squares. Given a parameter, θ, for which we have a quadratic unbiased estimator, θ̃, the test statistic, for the hypothesis of nullity of that parameter, is the quotient of the positive part by the negative part of such estimator. Using generalized polar coordinates it is possible to obtain selective generalized F tests which are especially powerful for selected families of alternatives. We build both classes of tests for the orthogonal and associated mixed models. The associated models are obtained adding terms to the orthogonal models.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2008, 28, 2; 229-246
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Orthogonal models: Algebraic structure and explicit estimators for estimable vectors
Autorzy:
Pereira, Artur
Fonseca, Miguel
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729750.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
linear models
mixed models
inference
orthogonal models
UBLUE
Opis:
We study the algebraic structure of orthogonal models thus of mixed models whose variance covariance matrices are all positive semi definite, linear combinations of known pairwise orthogonal projection matrices, POOPM, and whose least square estimators, LSE, of estimable vectors are best linear unbiased estimator, BLUE, whatever the variance components, so they are uniformly BLUE, UBLUE. From the results of the algebraic structure we will get explicit expression for the LSE of these models.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2015, 35, 1-2; 29-44
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exact distribution for the generalized F tests
Autorzy:
Fonseca, Miguel
Mexia, Joao
Zmyślony, Roman
Powiązania:
https://bibliotekanauki.pl/articles/729860.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
exact distribution theory
hypothesis testing
generalized F distribution
adaptative test
Opis:
Generalized F statistics are the quotients of convex combinations of central chi-squares divided by their degrees of freedom. Exact expressions are obtained for the distribution of these statistics when the degrees of freedom either in the numerator or in the denominator are even. An example is given to show how these expressions may be used to check the accuracy of Monte-Carlo methods in tabling these distributions. Moreover, when carrying out adaptative tests, these expressions enable us to estimate the p-values whenever they are available.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2002, 22, 1-2; 37-51
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Algebraic structureof step nesting designs
Autorzy:
Fernandes, Célia
Ramos, Paulo
Mexia, João
Powiązania:
https://bibliotekanauki.pl/articles/729913.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
commutative Jordan algebras
cartesian product of commutative Jordan algebras
step nesting
variance components
UMVUE
Opis:
Step nesting designs may be very useful since they require fewer observations than the usual balanced nesting models. The number of treatments in balanced nesting design is the product of the number of levels in each factor. This number may be too large. As an alternative, in step nesting designs the number of treatments is the sum of the factor levels. Thus these models lead to a great economy and it is easy to carry out inference. To study the algebraic structure of step nesting designs we introduce the cartesian product of commutative Jordan algebras.
Źródło:
Discussiones Mathematicae Probability and Statistics; 2010, 30, 2; 221-235
1509-9423
Pojawia się w:
Discussiones Mathematicae Probability and Statistics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 29

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