SORT (Statistics and Operations Research Transactions) (SORT-STAT OPER RES T)

Publisher: Institut d'Estadística de Catalunya

Current impact factor: 1.33

Impact Factor Rankings

2016 Impact Factor Available summer 2017
2014 / 2015 Impact Factor 1.333
2013 Impact Factor 0.962
2012 Impact Factor 0.462
2011 Impact Factor 0.429
2010 Impact Factor 0.25
2009 Impact Factor 0.368

Impact factor over time

Impact factor
Year

Additional details

5-year impact 1.13
Cited half-life -
Immediacy index 0.06
Eigenfactor 0.00
Article influence 0.52
Website SORT (Statistics and Operations Research Transactions) website
ISSN 1696-2281

Publisher details

Institut d'Estadística de Catalunya

  • Pre-print
    • Archiving status unclear
  • Post-print
    • Author cannot archive a post-print version
  • Conditions
    • Publisher's version/PDF must be used
    • Published source must be acknowledged
    • Creative Commons Attribution Non-Commercial No Derivatives License
    • All titles are open access journals
  • Classification
    blue

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, the exponentiated discrete Weibull distribution is introduced. This new generalization of the discrete Weibull distribution can also be considered as a discrete analog of the exponentiated Weibull distribution. A special case of this exponentiated discrete Weibull distribution defines a new generalization of the discrete Rayleigh distribution for the first time in the literature. In addition, discrete generalized exponential and geometric distributions are some special sub-models of the new distribution. Here, some basic distributional properties, moments, and order statistics of this new discrete distribution are studied. We will see that the hazard rate function can be increasing, decreasing, bathtub, and upside-down bathtub shaped. Estimation of the parameters is illustrated using the maximum likelihood method. The model with a real data set is also examined.
    No preview · Article · Feb 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: Classical discrete distributions rarely support modelling data on the set of whole integers. In this paper, we shall introduce a flexible discrete distribution on this set, which can, in addition, cover bimodal as well as unimodal data sets. The proposed distribution can also be fitted to positive and negative skewed data. The distribution is indeed a discrete counterpart of the continuous alpha-skew-Laplace distribution recently introduced in the literature. The proposed distribution can also be viewed as a weighted version of the discrete Laplace distribution. Several distributional properties of this class such as cumulative distribution function, moment generating function, moments, modality, infinite divisibility and its truncation are studied. A simulation study is also performed. Finally, a real data set is used to show applicability of the new model comparing to several rival models, such as the discrete normal and Skellam distributions.
    No preview · Article · Jan 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: In this paper we study a new class of skew-Cauchy distributions inspired on the family extended two-piece skew normal distribution. The new family of distributions encompasses three well known families of distributions, the normal, the two-piece skew-normal and the skew-normal-Cauchy distributions. Some properties of the new distribution are investigated, inference via maximum likelihood estimation is implemented and results of a real data application, which reveal good performance of the new model, are reported.
    No preview · Article · Jan 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: P-splines first appeared in the limelight twenty years ago. Since then they have become popular in applications and in theoretical work. The combination of a rich B-spline basis and a simple difference penalty lends itself well to a variety of generalizations, because it is based on regression. In effect, P-splines allow the building of a "backbone" for the "mixing and matching" of a variety of additive smooth structure components, while inviting all sorts of extensions: varying-coefficient effects, signal (functional) regressors, two-dimensional surfaces, non-normal responses, quantile (expectile) modelling, among others. Strong connections with mixed models and Bayesian analysis have been established. We give an overview of many of the central developments during the first two decades of P-splines.
    No preview · Article · Jan 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: High leverage collinearity influential observations are those high leverage points that change the multicollinearity pattern of a data. It is imperative to identify these points as they are responsible for misleading inferences on the fitting of a regression model. Moreover, identifying these observations may help statistics practitioners to solve the problem of multicollinearity, which is caused by high leverage points. A diagnostic plot is very useful for practitioners to quickly capture abnormalities in a data. In this paper, we propose new diagnostic plots to identify high leverage collinearity influential observations. The merit of our proposed diagnostic plots is confirmed by some well-known examples and Monte Carlo simulations.
    No preview · Article · Jan 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: Likelihood estimates of the Dirichlet distribution parameters can be obtained only through numerical algorithms. Such algorithms can provide estimates outside the correct range for the parameters and/or can require a large amount of iterations to reach convergence. These problems can be aggravated if good starting values are not provided. In this paper we discuss several approaches that can partially avoid these problems providing a good trade off between efficiency and stability. The performances of these approaches are compared on high-dimensional real and simulated data.
    No preview · Article · Jan 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: The analysis of markets with indivisible goods and fixed exogenous prices has played an important role in economic models, especially in relation to wage rigidity and unemployment. This paper provides a novel mathematical programming based approach to study pure exchange economies where discrete amounts of commodities are exchanged at fixed prices. Barter processes, consisting in sequences of elementary reallocations of couple of commodities among couples of agents, are formalized as local searches converging to equilibrium allocations. A direct application of the analysed processes in the context of computational economics is provided, along with a Java implementation of the described approaches.
    No preview · Article · Jan 2015 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: In recent years, kidney paired donation (KPD) has been extended to include living non-directed or altruistic donors, in which an altruistic donor donates to the candidate of an incompatible donor-candidate pair with the understanding that the donor in that pair will further donate to the candidate of a second pair, and so on; such a process continues and thus forms an altruistic donor-initiated chain. In this paper, we propose a novel strategy to sequentially allocate the altruistic donor (or bridge donor) so as to maximize the expected utility; analogous to the way a computer plays chess, the idea is to evaluate different allocations for each altruistic donor (or bridge donor) by looking several moves ahead in a derived look-ahead search tree. Simulation studies are provided to illustrate and evaluate our proposed method.
    No preview · Article · Oct 2014 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: In this article, a global hypothesis test is studied to simultaneously compare the likelihood ratios of multiple binary diagnostic tests when in the presence of partial disease verification the missing data mechanism is ignorable. The hypothesis test is based on the chi-squared distribution. Simulation experiments were carried out to study the type I error and the power of the global hypothesis test when comparing the likelihood ratios of two and three diagnostic tests respectively. The results obtained were applied to the diagnosis of coronary stenosis.
    No preview · Article · Jul 2014 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: In this paper, a general method for predicting future lower and upper current records and record range from any arbitrary continuous distribution is proposed. Two pivotal statistics with the same explicit distribution for lower and upper current records are developed to construct prediction intervals for future current records. In addition, prediction intervals for future observations of the record range are constructed. A simulation study is applied on normal and Weibull distributions to investigate the efficiency of the suggested method. Finally, an example for real lifetime data with unknown distribution is analysed.
    No preview · Article · Jul 2014 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: The main aim of this paper is to give a systematization on the stochastic cash flows evolution. The tools that are used for this purpose are discrete time semi-Markov reward processes. The paper is directed not only to semi-Markov researchers but also to a wider public, presenting a full treatment of these tools both in homogeneous and non-homogeneous environment. The main result given in the paper is the natural correspondence of the stochastic cash flows with the semi-Markov reward processes. Indeed, the semi-Markov environment gives the possibility to follow a multi-state random system in which the randomness is not only in the transition to the next state but also in the time of transition. Furthermore, rewards permit the introduction of a financial environment into the model. Considering all these properties, any stochastic cash flow can be naturally modelled by means of semi-Markov reward processes. The backward case offers the possibility of considering in a complete way the duration inside a state of the studied system and this fact can be very useful in the evaluation of insurance contracts.
    No preview · Article · Jul 2014 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: There has been recently a striking increase in the use of propensity score methods in health sciences research as a tool to adjust for selection bias in making causal inferences from observational controlled studies. However, reviews of published studies that use these techniques suggest that investigators often do not pay proper attention to thorough verification of appropriate fulfilment of propensity score adjusting properties. By using a case study in which balance is not achieved, we illustrate the need to systematically asses the accomplishment of the balancing property of the propensity score as a critical requirement for obtaining unbiased treatment effects estimates.
    No preview · Article · Jul 2014 · SORT (Statistics and Operations Research Transactions)
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    ABSTRACT: This paper introduces an extension of the slash-elliptical distribution. This new distribution is generated as the quotient between two independent random variables, one from the elliptical family (numerator) and the other (denominator) a beta distribution. The resulting slash-elliptical distribution potentially has a larger kurtosis coefficient than the ordinary slash-elliptical distribution. We investigate properties of this distribution such as moments and closed expressions for the density function. Moreover, an extension is proposed for the location scale situation. Likelihood equations are derived for this more general version. Results of a real data application reveal that the proposed model performs well, so that it is a viable alternative to replace models with lesser kurtosis flexibility. We also propose a multivariate extension.
    No preview · Article · Jul 2014 · SORT (Statistics and Operations Research Transactions)