accedaCRIShttps://accedacris.ulpgc.es/jspuiThe accedaCRIS digital repository system captures, stores, indexes, preserves, and distributes digital research material.Tue, 21 Mar 2023 12:17:26 GMT2023-03-21T12:17:26Z5091An alternative representation of the negative binomial-Lindley distribution. New results and applicationshttp://hdl.handle.net/10553/41626Title: An alternative representation of the negative binomial-Lindley distribution. New results and applications
Authors: Gómez-Déniz, Emilio; Calderin-Ojeda, Enrique
Abstract: In this paper we present an alternative representation of the Negative Binomial--Lindley distribution recently proposed by Zamani and Ismail (2010) which shows some advantages over the latter model. This new formulation
provides a tractable model with attractive properties which makes it suitable for application not only in insurance settings but also in other fields where overdispersion is observed. Basic properties of the new distribution are
studied. A recurrence for the probabilities of the new distribution and an integral equation for the probability density function of the compound version, when the claim severities are absolutely continuous, are derived. Estimation
methods are discussed and a numerical application is given.
Sun, 01 Jan 2017 00:00:00 GMThttp://hdl.handle.net/10553/416262017-01-01T00:00:00ZThe Geometric ArcTan distribution with applications to model demand for health serviceshttp://hdl.handle.net/10553/41589Title: The Geometric ArcTan distribution with applications to model demand for health services
Authors: Gómez-Déniz, E.; Sarabia, J. M.; Calderín-Ojeda, Enrique
Abstract: In this paper, a new discrete two–parameter distribution α ∈ ℜ − {0} and 0 < θ < 1, the Geometric ArcTan (GAT) distribution is introduced. The geometric distribution is a limiting case of this model when α tends to zero. Similarly to the the latter distribution, this probabilistic family is unimodal but the mode can be located at zero or in other point of the support. Then, after deriving some of its more relevant properties, the issue of parameter investigation is investigated. Next, the GAT distribution is used to explain the demand for health services by means of a regression model. Numerical results show that this new model outperforms the negative binomial distribution.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10553/415892018-01-01T00:00:00ZMultivariate credibility in bonus-malus systems distinguishing between different types of claimshttp://hdl.handle.net/10553/69779Title: Multivariate credibility in bonus-malus systems distinguishing between different types of claims
Authors: Gómez Déniz, Emilio; Calderín Ojeda,Enrique
Abstract: In the classical bonus-malus system the premium assigned to each policyholder is based only on the number of claims made without having into account the claims size. Thus, a policyholder who has declared a claim that results in a relatively small loss is penalised to the same extent as one who has declared a more expensive claim. Of course, this is seen unfair by many policyholders. In this paper, we study the factors that affect the number of claims in car insurance by using a trivariate discrete distribution. This approach allows us to discern between three types of claims depending wether the claims are above, between or below certain thresholds. Therefore, this model implements the two fundamental random variables in this scenario, the number of claims as well as the amount associated with them. In addition, we introduce a trivariate prior distribution conjugated with this discrete distribution that produce credibility bonus-malus premiums that satisfy appropriate traditional transition rules. A practical example based on real data is shown to examine the differences with respect to the premiums obtained under the traditional system of tarification.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10553/697792018-01-01T00:00:00ZBayesian robustness in meta-analysis for studies with zero responseshttp://hdl.handle.net/10553/42493Title: Bayesian robustness in meta-analysis for studies with zero responses
Authors: Vázquez Polo, Francisco José; Moreno, E.; Negrín, M. A.; Martel, M.
Abstract: Statistical meta-analysis is mostly carried out with the help of the random effect normal model, including the case of discrete random variables. We argue that the normal approximation is not always able to adequately capture the underlying uncertainty of the original discrete data. Furthermore, when we examine the influence of the prior distributions considered, in the presence of rare events, the results from this approximation can be very poor. In order to assess the robustness of the quantities of interest in meta-analysis with respect to the choice of priors, this paper proposes an alternative Bayesian model for binomial random variables with several zero responses. Particular attention is paid to the coherence between the prior distributions of the study model parameters and the meta-parameter. Thus, our method introduces a simple way to examine the sensitivity of these quantities to the structure dependence selected for study. For illustrative purposes, an example with real data is analysed, using the proposed Bayesian meta-analysis model for binomial sparse data.
Fri, 01 Jan 2016 00:00:00 GMThttp://hdl.handle.net/10553/424932016-01-01T00:00:00ZModelling tourist expenditure at origin and destinationhttp://hdl.handle.net/10553/55443Title: Modelling tourist expenditure at origin and destination
Authors: Gómez Déniz, Emilio; Pérez Rodríguez, Jorge Vicente; Boza Chirino, Jose
Abstract: This article proposes a model of foreign tourist expenditure, based on expenditure in the country of origin (i.e. reservation of accommodation and transport) and on goods and services at the destination. The study focuses on two measures reflecting the two types of expenditure: the tourist budget share and the difference in growth rates between expenditure at origin and at destination. The random nature of each of these variables is taken into account. The tourist budget share is determined using a fractional response model, based on the beta distribution. This approach allows us to accommodate certain aspects of the empirical budget share distribution, such as skewness, and to represent the results as bounded between 0 and 1, but also to include covariates. The empirical analysis was conducted using data obtained by the Canary Islands Tourist Expenditure Survey, focusing on German and British tourists in particular. The results obtained show that the fractional regression model proposed represents the behaviour of the relevant variables reasonably well and surpasses the performance of the linear regression model.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10553/554432020-01-01T00:00:00ZQuasi-binomial zero-inflated regression model suitable for variables with bounded supporthttp://hdl.handle.net/10553/70163Title: Quasi-binomial zero-inflated regression model suitable for variables with bounded support
Authors: Gómez Déniz, Emilio; Gallardo, D. I.; Gómez, H. W.
Abstract: In recent years, a variety of regression models, including zero-inflated and hurdle versions, have been proposed to explain the case of a dependent variable with respect to exogenous covariates. Apart from the classical Poisson, negative binomial and generalised Poisson distributions, many proposals have appeared in the statistical literature, perhaps in response to the new possibilities offered by advanced software that now enables researchers to implement numerous special functions in a relatively simple way. However, we believe that a significant research gap remains, since very little attention has been paid to the quasi-binomial distribution, which was first proposed over fifty years ago. We believe this distribution might constitute a valid alternative to existing regression models, in situations in which the variable has bounded support. Therefore, in this paper we present a zero-inflated regression model based on the quasi-binomial distribution, taking into account the moments and maximum likelihood estimators, and perform a score test to compare the zero-inflated quasi-binomial distribution with the zero-inflated binomial distribution, and the zero-inflated model with the homogeneous model (the model in which covariates are not considered). This analysis is illustrated with two data sets that are well known in the statistical literature and which contain a large number of zeros.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/10553/701632020-01-01T00:00:00ZAnalyzing How the Social Security Reserve Fund in Spain Affects the Sustainability of the Pension Systemhttp://hdl.handle.net/10553/121374Title: Analyzing How the Social Security Reserve Fund in Spain Affects the Sustainability of the Pension System
Authors: Gómez Déniz, Emilio; Pérez-Rodríguez, Jorge V.; Sosvilla Rivero,Simón Javier
Abstract: Faced with the need to adjust public pension systems to meet changing demographic, economic and social conditions, most developed countries have created government reserve funds to ensure macroeconomic sustainability. This paper aims to study the importance that this reserve fund plays in the sustainability of the Spanish public pension system. Using data for the 2000 to 2019 period (20 observations) on the main variables impacting on the system, we calculate probabilities and other indicators of its unsustainability in relation to the reserve fund. Our model accurately reflects certain aspects of the data, and suggests that the probability of unsustainability is inversely associated with the size of the reserve fund, but that this relation is moderated by the heterogeneity of the members of the pension system. Moreover, the probability of unsustainability increases in line with the pension system deficit, the time elapsed until unsustainability is reached is shorter when the Reserve Fund balance falls, and the size of this fund at which the system becomes unsustainable diminishes with the probability of unsustainability.
Sat, 01 Jan 2022 00:00:00 GMThttp://hdl.handle.net/10553/1213742022-01-01T00:00:00ZThe Slashed-Rayleigh fading channel distributionhttp://hdl.handle.net/10553/56176Title: The Slashed-Rayleigh fading channel distribution
Authors: Gómez Déniz, Emilio; Gómez Déniz, Luis; Gómez, H. W.
Abstract: We propose an alternative distribution for modelling fading-shadowing wireless channels. This distribution presents certain advantages over the Rayleigh-lognormal distribution and the K distribution and has proved useful in the setting described. We obtain closed-form expressions for the average channel capacity and for the average bit error rate of differential phase-shift keying and of minimum shift keying when the new distribution is used. This distribution can be obtained exactly as the sum of mutual independent Gaussian stochastic processes, because it must represent the simulation of the fading channel; that is, it simulates the signal envelope. Finally, we describe practical applications of this distribution, comparing it with the Rayleigh-lognormal and K distributions.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10553/561762019-01-01T00:00:00ZModified power-symmetric distributionhttp://hdl.handle.net/10553/70120Title: Modified power-symmetric distribution
Authors: Gómez Déniz, Emilio; Iriarte, Yuri A.; Calderín Ojeda,Enrique; Gómez, Héctor W.
Abstract: In this paper, a general class of modified power-symmetric distributions is introduced. By choosing as symmetric model the normal distribution, the modified power-normal distribution is obtained. For the latter model, some of its more relevant statistical properties are examined. Parameters estimation is carried out by using the method of moments and maximum likelihood estimation. A simulation analysis is accomplished to study the performance of the maximum likelihood estimators. Finally, we compare the efficiency of the modified power-normal distribution with other existing distributions in the literature by using a real dataset.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/10553/701202019-01-01T00:00:00Z