Pakistan Journal of Statistics and Operation Research
http://www.pjsor.com/index.php/pjsor
Pakistan Journal of Statistics and Operation Researchen-US<p><strong>Authors who publish with this journal agree to the following terms:</strong></p><ul><li>Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a <a href="http://creativecommons.org/licenses/by/3.0/" target="_new">Creative Commons Attribution License</a> that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li></ul><div> </div><ul><li>Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li></ul><div> </div><ul><li>Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See <a href="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li></ul><p><span><br /></span></p>editor@pjsor.com (Dr. Shahid Kamal)annum@pjsor.com (Support Team)Fri, 09 Mar 2018 16:06:11 +0000OJS 2.4.5.0http://blogs.law.harvard.edu/tech/rss60Odds Generalized Exponential-Inverse Weibull Distribution: Properties & Estimation
http://www.pjsor.com/index.php/pjsor/article/view/2086
Providing extended and generalized distribution is usually precious for many statisticians. A new distribution, called odds generalized exponential-inverse Weibull distribution (OGE-IW) is suggested for modeling lifetime data. Some structural properties of the new distribution are obtained. Three different estimation procedures, namely; maximum likelihood, percentiles and least squares, have been used to estimate the model parameters of subject distribution. The consistency of the parameters of the OGE-IW distribution is demonstrated through a simulation study. A real data application is presented to illustrate the importance of the new distribution compared with some known distributions.Amal Soliman Hassan, Elsayed Ahmed Elsherpieny, Rokaya Elmorsy Mohamedhttp://www.pjsor.com/index.php/pjsor/article/view/2086Fri, 09 Mar 2018 00:00:00 +0000Nonparametric Confidence Interval for Quantiles
http://www.pjsor.com/index.php/pjsor/article/view/2071
<p>Quantiles, which are also known as values-at-risk in finance, frequently arise in practice as measures of risk. Confidence interval for quantiles are typically constructed via large sample theory or the sectioning.</p><p>One of the ways for achieving the confidence interval for quantiles is direct use of a central limit theorem. In this approach, we require a good estimator of the quantile density function. In this paper, we consider the nonparametric estimator of the quantile density function from Soni et al. (2012) and we obtain confidence interval for quantiles. In the following, by using simulation, the coverage probability and mean square error of this confidence interval is calculated. Also, we compare our proposed approach with alternative approaches such as sectioning and jackknife.</p>Mohammad Bolbolian Ghalibafhttp://www.pjsor.com/index.php/pjsor/article/view/2071Fri, 09 Mar 2018 00:00:00 +0000Type I General Exponential Class of distributions
http://www.pjsor.com/index.php/pjsor/article/view/2193
We introduce a new family of continuous distributions and study the mathematical properties of the new family. Some useful characterizations based on the ratio of two truncated moments and hazard function are also presented. We estimate the model parameters by the maximum likelihood method and assess its performance based on biases and mean squared errors in a simulation study framework.Dr. G.G. Hamedani, Haitham M. Yousof, Mahdi Rasekhi, Morad Alizadeh, Seyed Morteza Najibihttp://www.pjsor.com/index.php/pjsor/article/view/2193Fri, 09 Mar 2018 00:00:00 +0000The Exponentiated Marshall-Olkin Fréchet Distribution
http://www.pjsor.com/index.php/pjsor/article/view/2286
<p>A new five-parameter model called the exponentiated Marshall-Olkin Fréchet distribution is studied. Various of its mathematical properties including ordinary and incomplete moments, quantile and generating functions and order statistics are investigated. The proposed density function can be expressed as a linear mixture of Fréchet densities. The maximum likelihood method is used to estimate the model parameters. The flexibility of the new distribution is proved empirically using two real data sets.</p>Mahmoud M. Mansour, Enayat M. Abd Elrazik, Nadeem Shafique Butthttp://www.pjsor.com/index.php/pjsor/article/view/2286Thu, 01 Mar 2018 00:00:00 +0000A New Multivariate Weibull Distribution
http://www.pjsor.com/index.php/pjsor/article/view/2192
We have proposed a new multivariate Weibull distribution as a compound distribution of univariate Weibull distributions. We have studied some properties of the proposed distribution. The multivariate distribution of records for proposed distribution has also been studied. Estimation of the parameters has been done alongside application to the real data set.Saman Hanif Shahbaz, Mashail Al-Sobhi, Muhammad Qaiser Shahbaz, Bander Al-Zahranihttp://www.pjsor.com/index.php/pjsor/article/view/2192Fri, 09 Mar 2018 00:00:00 +0000Regression Estimators in Ranked Set, Median Ranked Set and Neoteric Ranked Set Sampling
http://www.pjsor.com/index.php/pjsor/article/view/1825
This paper proposes new regression estimators in median ranked set and neoteric ranked set sampling using one and two auxiliary variables. The proposed estimators have large gain in presicion compared to the classical ranked set sampling (RSS) design. A simulation study is designed to see the performance of suggested estimators. A real data set example is also used. In this data set, we have examined a rare endemic annual plant species which is grown in Turkey. We have found that suggested estimators are highly efficient that existing estimators.Nursel Koyuncuhttp://www.pjsor.com/index.php/pjsor/article/view/1825Fri, 09 Mar 2018 00:00:00 +0000Optimization of Surplus Reinsurance Treaty using the Conditional Tail Expectation
http://www.pjsor.com/index.php/pjsor/article/view/1973
<p>In this work, we propose a new optimization strategy for reinsurance using the genetic algorithms. This approach is to determine an optimal structure of a "surplus" reinsurance contract by finding the optimal cession rates through an optimization model which is based on the minimization of the Conditional Tail Expectation (CTE) risk measure under the constraint of technical benefit. This approach can be seen as a decision support tool that can be used by managers to minimize the actuarial risk and maximize the technical benefit in the insurance company.</p>Abderrahim El Attar, Mostafa El Hachloufi, Guennoun Zine El Abidinehttp://www.pjsor.com/index.php/pjsor/article/view/1973Fri, 09 Mar 2018 00:00:00 +0000Parameter Estimations and Optimal Design of Simple Step-Stress Model for Gamma Dual Weibull Distribution
http://www.pjsor.com/index.php/pjsor/article/view/1671
This paper considers life-testing experiments and how it is effected by stress factors: namely temperature, electricity loads, cycling rate and pressure. A major type of accelerated life tests is a step-stress model that allows the experimenter to increase stress levels more than normal use during the experiment to see the failure items. The test items are assumed to follow Gamma Dual Weibull distribution. Different methods for estimating the parameters are discussed. These include Maximum Likelihood Estimations and Confidence Interval Estimations which is based on asymptotic normality generate narrow intervals to the unknown distribution parameters with high probability. MathCAD (2001) program is used to illustrate the optimal time procedure through numerical examples.Hamdy Mohamed Salemhttp://www.pjsor.com/index.php/pjsor/article/view/1671Fri, 09 Mar 2018 00:00:00 +0000A Generalization of Generalized Gamma Distributions
http://www.pjsor.com/index.php/pjsor/article/view/1692
<p>For the first time, a new generalization of generalized gamma distribution called the modified generalized gamma distribution has been introduced to provide greater flexibility in modeling data from a practical viewpoint. The new distribution generalizes some recently introduced generalizations of the gamma distribution. Various properties of the proposed distribution, including explicit expressions for the moments, quantiles, mode, moment generating function, mean deviation, mean residual lifetime and expression of the entropies are derived. The distribution is capable of monotonically increasing, decreasing, bathtub-shaped, and upside-down bathtub-shaped hazard rates. The maximum likelihood estimators of unknown parameters cannot be obtained in explicit forms, and they have to be obtained by solving non-linear equations only. Two real data sets have been analyzed to show how the proposed models work in practice.</p>Mohamed Mead, Mazen Mohammed Nassar, Sanku Deyhttp://www.pjsor.com/index.php/pjsor/article/view/1692Fri, 09 Mar 2018 00:00:00 +0000Generalized Version of Complementary Lindley Power Series Distribution
http://www.pjsor.com/index.php/pjsor/article/view/1987
<p>In this paper, we shall introduce a new class of generalized complementary compound lifetime distributions which is obtained by compounding generalized Lindley distribution with power series distribution. This new family of continuous lifetime distributions so obtained will be called Complementary Generalized Lindley Power Series (CGLPS) distribution. The proposed class of distribution contains several lifetime distributions as its special cases that are very flexible to accommodate different types of data sets since the probability density function and hazard rate can take up different forms such as increasing, decreasing and upside down bathtub shapes which have been shown through graphs for some selected values of parameters and the potentiality proposed class has been tested statistically by using it to model some real life data set.</p>Zahoor Ahmad, Adil Rashid, T. R. Janhttp://www.pjsor.com/index.php/pjsor/article/view/1987Fri, 09 Mar 2018 15:52:39 +0000Moment Properties And Quadratic Estimating Functions For Integer-Valued Time Series Models
http://www.pjsor.com/index.php/pjsor/article/view/1750
Recently, there has been a growing interest in integer-valued volatility models. In this paper, using a martingale transformation, a general theorem on moment properties of a class of integer-valued volatility models is given with simpler proof. We show that the first two moments obtained in the recent literature are special cases. In addition, we also derive the closed form expressions of the kurtosis and skewness formula for the models. The results are very useful in understanding the behaviour of the process and in estimating the parameters of the models using quadratic estimating functions method. Specifically, we derive the optimal function of INGARCH(1,1) and obtain the estimated parameters of interest via simulation. We show that the performance of the quadratic estimating functions method is superior compared to maximum likelihood and least square methods. For illustration, we fit the INGARCH(1,1) on 108 monthly strike data from January 1994 to December 2002 from Jung et al. (2005).Ibrahim Mohamed, Nurul Najihah, Ng Kok Haurhttp://www.pjsor.com/index.php/pjsor/article/view/1750Fri, 09 Mar 2018 15:54:09 +0000On Characterizations of McLLoG, ELLoGW, PTHL and k-GE Distributions
http://www.pjsor.com/index.php/pjsor/article/view/2263
<p><span style="font-size: medium;">Huang S. and Oluyede (2016), Oluyede et al. (2016), Krishnarani (2016) and Rather and Rather (2017) consider the "McDonald Log-Logistic", the "Exponentiated Log-Logistic Weibull", the "Power Transformation Half-Logistic" and "k-Generalized Exponential" distributions, respectively, and study certain properties and applications of these distributions. </span><span style="font-size: medium;">The present short note is intended to complete, in some way, the above mentioned works via establishing certain characterizations of these distributions in different directions.</span></p>G.G. Hamedani, Nadeem Shafique Butthttp://www.pjsor.com/index.php/pjsor/article/view/2263Thu, 01 Mar 2018 00:00:00 +0000Steady-State Behavior of Nonparametric Synthetic Control Chart Using Signed-Rank Statistic
http://www.pjsor.com/index.php/pjsor/article/view/2029
<p>If process is running for a long period in an in-control condition, it will reach in a steady-state condition. In order to study the long term properties of a control chart, it is appropriate to investigate the steady-state average run length. In this paper we study zero-state and steady-state behaviour of a nonparametric synthetic control chart using signed-rank statistic. The zero-state average time to signal and steady-state average time to signal are computed using Markov chain approach. In Comparison study, steady-state average time to signal is compared with zero-state average time to signal for various symmetric distributions. Usefulness of the proposed control chart explored through by giving numerical example.</p>Vilas Y Pawar, Digambar Tukaram Shirke, Shashikant Kuber Khilarehttp://www.pjsor.com/index.php/pjsor/article/view/2029Fri, 09 Mar 2018 00:00:00 +0000