Publications

Export 75 results:
Sort by: Author Title [ Type  (Asc)] Year
Conference Proceedings
Gomes, M. I., & Caeiro F. (2014).  Eficiency of partially reduced-bias mean-of-order-p versus minimum-variance reduced-bias extreme value index estimation. COMPSTAT 2014: 21th International Conference on Computational Statistics. 289-298., Jan, Geneve Abstractgomes_caeiro_compstat2014_reprint.pdf

n/a

Caeiro, F., & Gomes M. I. (2006).  Estimação de quantis elevados em estatística de extremos. Actas do XIII Congresso Anual da Sociedade Portuguesa de Estatística - "Ciência Estatística". 217-228.2006spe217-228.pdf
Caeiro, F., & Gomes M. I. (2014).  On the bootstrap methodology for the estimation of the tail sample fraction. COMPSTAT 2014: 21th International Conference on Computational Statistics. 546-553., Genevecaeiro_gomes_compstat2014_reprint.pdf
M.I., G., F. C., & L. H. - R. (2012).  PORT-PPWM extreme value index estimation. Proceedings of COMPSTAT 2012. 259-270., Jan Abstract2012_compstat2012.pdf

n/a

Caeiro, F., & Gomes M. I. (2006).  Redução de viés na estimação semi-paramétrica de um parâmetro de escala. Actas do XIII Congresso da SPE - "Ciência Estatística". 127-148.2006spe_127-148.pdf
F., C., & M.I. G. (2012).  A Reduced Bias Estimator of a 'Scale' Second Order Parameter. 1114-1117., Jan, Number 1479 Abstract

n/a

Caeiro, F. (2003).  Redução de viés em estimadores do índice de cauda. Actas do X Congresso Anual da SPE - “Literacia e Estatística”. 187-199., Porto, Portugalspe2002_187-199.pdf
Caeiro, F., & Gomes M. I. (2007).  Second-order Reduced-bias Tail Index and High Quantile Estimation. 56th SESSION OF THE INTERNATIONAL STATISTICAL INSTITUTE. 109-116., Lisbon, Portugal2007isi_volume_lxii_proceedings_caeiro_gomes.pdf
Caeiro, F., & Gomes M. I. (2005).  Uma classe de estimadores do parâmetro de escala de segunda ordem.. Actas do XII Congresso Anual da Sociedade Portuguesa de Estatística. 113-124., Évora, Portugalcaeirof-spe2004.pdf
Journal Article
Caeiro, F., & Gomes M. I. (2010).  An asymptotically unbiased moment estimator of a negative extreme value index.. Discuss. Math., Probab. Stat.. 30, 5-19., Number 1 Abstract

{Summary: We consider a new class of consistent semi-parametric estimators of a negative extreme value index, based on the set of the $k$ largest observations. This class of estimators depends on a control or tuning parameter, which enables us to have access to an estimator with a null second-order component of asymptotic bias, and with a rather interesting mean squared error, as a function of $k$. We study the consistency and asymptotic normality of the proposed estimators. Their finite sample behaviour is obtained through Monte Carlo simulation.}

Caeiro, F., & Gomes I. M. (2015).  Bias reduction in the estimation of a shape second-order parameter of a heavy-tailed model. Journal Of Statistical Computation And SimulationJournal Of Statistical Computation And Simulation. 85(17), 3405 - 3419., 2015 AbstractWebsite

In extreme value theory, the shape second-order parameter is a quite relevant parameter related to the speed of convergence of maximum values, linearly normalized, towards its limit law. The adequate estimation of this parameter is vital for improving the estimation of the extreme value index, the primary parameter in statistics of extremes. In this article, we consider a recent class of semi-parametric estimators of the shape second-order parameter for heavy right-tailed models. These estimators, based on the largest order statistics, depend on a real tuning parameter, which makes them highly flexible and possibly unbiased for several underlying models. In this article, we are interested in the adaptive choice of such tuning parameter and the number of top order statistics used in the estimation procedure. The performance of the methodology for the adaptive choice of parameters is evaluated through a Monte Carlo simulation study.In extreme value theory, the shape second-order parameter is a quite relevant parameter related to the speed of convergence of maximum values, linearly normalized, towards its limit law. The adequate estimation of this parameter is vital for improving the estimation of the extreme value index, the primary parameter in statistics of extremes. In this article, we consider a recent class of semi-parametric estimators of the shape second-order parameter for heavy right-tailed models. These estimators, based on the largest order statistics, depend on a real tuning parameter, which makes them highly flexible and possibly unbiased for several underlying models. In this article, we are interested in the adaptive choice of such tuning parameter and the number of top order statistics used in the estimation procedure. The performance of the methodology for the adaptive choice of parameters is evaluated through a Monte Carlo simulation study.

Caeiro, F., & Gomes I. M. (2002).  Bias reduction in the estimation of parameters of rare events.. Theory of Stochastic Processes. 8(24), 67-76. Abstract2002tsp_caeiro_gomes.pdf

{Consider the distribution function $EV_{\gamma}(x)=\exp(-(1+\gamma x)^{- 1/\gamma}),\ \gamma>0,\ 1+\gamma x>0$, to which $\max(X_{1},łdots, X_{n})$ is attracted after suitable linear normalization. The authors consider the underlying model $F$ in the max-domain of attraction of $EV_{\gamma}$, where $ X_{i:n},\ 1łeq Iłeq n$, denotes the i-th ascending order statistic associated to the random sample $(X_{1},łdots, X_{n})$ from the unknown distribution function $F$. This article is devoted to studying semi-parametric estimators of $\gamma$ in the form $$\gamma_{n}^{(þeta,\alpha)}(k)=(\Gamma(\alpha)/M_{n}^{(\alpha- 1)}(k))łeft(M_{n}^{(þeta\alpha)}(k)/\Gamma(þeta\alpha+1)\right) ^{1/þeta},\quad \alpha\geq 1,\quad þeta>0,$$ parametrized by the parameters $\alpha$ and $þeta$, which may be controlled, where $M_{n}^{(0)}=1$ and $ M_{n}^{(\alpha)}(k)=k^{-1}\sum_{i=1}^{k}(łn X_{n-i+1:n}-łn X_{n-k:n})^{\alpha}$, $\alpha>0$, is a consistent estimator of $\Gamma(\alpha+1)\gamma^{\alpha}$, as $k\toınfty$, and $k=o(n)$, as $n\toınfty$.\par The authors derive the asymptotic distributional properties of the considered class of estimators and obtain that for $þeta>1$ it is always possible to find a control parameter $\alpha$ which makes the dominant component of the asymptotic bias of the proposed estimator null and depends on the second order parameter $\rho$. An investigation of the $\rho$-estimator is presented.}

Gomes, M. I., Caeiro F., & Figueiredo F. (2004).  Bias reduction of a tail index estimator through an external estimation of the second-order parameter.. Statistics. 38, 497-510., Number 6 Abstract

{Summary: We first consider a class of consistent semi-parametric estimators of a positive tail index $\gamma$, parametrised in a tuning or control parameter $\alpha$. Such a control parameter enables us to have access for any available sample, to an estimator of the tail index $\gamma$ with a null dominant component of asymptotic bias and consequently with a reasonably flat mean squared error pattern, as a function of $k$, the number of top-order statistics considered.\par Such a control parameter depends on a second-order parameter $\rho$, which will be adequately estimated so that we may achieve a high efficiency relative to the classical Hill estimator [ıt B. M. Hill}, Ann. Stat. 3, 1163–1174 (1975; Zbl 0323.62033)] provided we use a number of top-order statistics larger than the one usually required for the estimation through the Hill estimator. An illustration of the behaviour of the estimators is provided, through the analysis of the daily log-returns on the Euro-US\$ exchange rates.}

Caeiro, F., & Gomes I. M. (2002).  A class of asymptotically unbiased semi-parametric estimators of the tail index.. Test. 11, 345-364., Number 2 Abstract

{Summary: We consider a class of consistent semi-parametric estimators of a positive tail index $\gamma$, parameterized by a tuning or control parameter $\alpha$. Such a control parameter enables us to have access, for any available sample, to an estimator of $\gamma$ with a null dominant component of asymptotic bias, and with a reasonably flat mean squared error pattern, as a function of $k$, the number of top order statistics considered. Moreover, we are able to achieve a high efficiency relative to the classical Hill estimator [ıt B. M. Hill}, Ann. Stat. 3, 1163–1174 (1975; Zbl 0323.62033)], provided we may have access to a larger number of top order statistics than the number needed for optimal estimation through the Hill estimator.}

Caeiro, F., Mateus A., & Soltane L. (2021).  A class of weighted Hill estimators. Computational and Mathematical Methods. , may: Wiley AbstractWebsite
n/a
Mateus, A., & Caeiro F. (2022).  Confidence Intervals for the Shape Parameter of a Pareto Distribution. AIP Conference Proceedings. 2425, Abstract
n/a
Gomes, M. I., Caeiro F., Figueiredo F., Henriques-Rodrigues L., & Pestana D. (2020).  Corrected-Hill versus partially reduced-bias value-at-risk estimation. Communications in Statistics: Simulation and Computation. 49, 867-885., Number 4 Abstract
n/a
Penalva, H., Ivette Gomes M., Caeiro F., & Manuela Neves M. (2020).  A couple of non reduced bias generalized means in extreme value theory: An asymptotic comparison. Revstat Statistical Journal. 18, 281-298., Number 3 Abstract
n/a
Caeiro, F., Gomes M. I., & Pestana D. (2005).  Direct reduction of bias of the classical Hill estimator.. REVSTAT. 3, 113-136., Number 2 Abstract

{Summary: We are interested in an adequate estimation of the dominant component of the bias of ıt B. M. Hill}\,'s estimator [Ann. Stat. 3, 1163–1174 (1975; Zbl 0323.62033)] of a positive tail index $\gamma$, in order to remove it from the classical Hill estimator in different asymptotically equivalent ways. If the second order parameters in the bias are computed at an adequate level $k_1$ of a larger order than that of the level $k$ at which the Hill estimator is computed, there may be no change in the asymptotic variances of these reduced bias tail index estimators, which are kept equal to the asymptotic variance of the Hill estimator, i.e., equal to $\gamma^2$. The asymptotic distributional properties of the proposed estimators of $\gamma$ are derived and the estimators are compared not only asymptotically, but also for finite samples through Monte Carlo techniques.}

Caeiro, F., & Mateus A. (2022).  Exponential versus Generalized Exponential Distribution: a Computational Study. AIP Conference Proceedings. 2425, Abstract
n/a
Mateus, A., & Caeiro F. (2022).  Improved Shape Parameter Estimation for the Three-Parameter Log-Logistic Distribution. (Qichun Zhang, Ed.).Computational and Mathematical Methods. 2022, 1–13., feb: Hindawi Limited AbstractWebsite
n/a
Penalva, H., Gomes M. I., Caeiro F., & Neves M. M. (2020).  Lehmer{'}s mean-of-order-p extreme value index estimation: a simulation study and applications. Journal of Applied Statistics. 47, 2825-2845., Number 13-15 Abstract
n/a