Ahmad shafay

Ahmad shafay


Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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4 December 2016 in Journal of Statistical Computation and Simulation
Verified
Journal Article
Closed access
MEM. M. M. Mohie El-Din
M. M. M. Mohie El-Din
MAM. M. Amein
M. M. Amein
ASAhmad shafay
Ahmad shafay
SMSamar Mohamed
Samar Mohamed
In this paper, based on an adaptive Type-II progressively censored sample from the generalized exponential distribution, the maximum likelihood and Bayesian estimators are derived for the unknown parameters as well as the reliability and hazard functions. Also, the approximate confidence intervals of the unknown parameters, and the reliability and hazard functions are calculated. Markov chain Monte Carlo method is applied to carry out a Bayesian estimation procedure and in turn calculate the credible intervals. Moreover, results from simulation studies assessing the performance of our proposed method are included. Finally, an illustrative example using real data set is presented for illustrating all the inferential procedures developed here.

1 July 2017 in Computational Statistics
Verified
Journal Article
Closed access
PDF file
MMMarwa Mostafa
Marwa Mostafa
ASAhmad shafay
Ahmad shafay
Magdy NagyMagdy Nagy
Magdy Nagy

18 November 2015 in Communications in Statistics - Simulation and Computation
Verified
Journal Article
Closed access
ASAhmad shafay
Ahmad shafay
In this article, the simple step-stress model is considered based on generalized Type-I hybrid censored data from the exponential distribution. The maximum likelihood estimators (MLEs) of the unknown parameters are derived assuming a cumulative exposure model. We then derive the exact distributions of the MLEs of the parameters using conditional moment generating functions. The Bayesian estimators of the parameters are derived and then compared with the MLEs. We also derive confidence intervals for the parameters using these exact distributions, asymptotic distributions of the MLEs, Bayesian, and the parametric bootstrap methods. The problem of determining the optimal stress-changing point is discussed and the MLEs of the pth quantile and reliability functions at the use condition are obtained. Finally, Monte Carlo simulation and some numerical results are presented for illustrating all the inferential methods developed here.

11 October 2015 in Journal of Statistical Computation and Simulation
Verified
Journal Article
Closed access
ASAhmad shafay
Ahmad shafay
In this paper, we consider a general form for the underlying distribution and a general conjugate prior, and develop a general procedure for deriving the maximum likelihood and Bayesian estimators based on an observed generalized Type-II hybrid censored sample. The problems of predicting the future order statistics from the same sample and that from a future sample are also discussed from a Bayesian viewpoint. For the illustration of the developed results, the exponential and Pareto distributions are used as examples. Finally, two numerical examples are presented for illustrating all the inferential procedures developed here.

18 February 2016 in Communications in Statistics - Theory and Methods
Verified
Journal Article
Closed access
ASAhmad shafay
Ahmad shafay
NBN. Balakrishnan
N. Balakrishnan
JAJafar Ahmadi
Jafar Ahmadi
In this paper, the two-parameter Pareto distribution is considered and the problem of prediction of order statistics from a future sample and that of its geometric mean are discussed. The Bayesian approach is applied to construct predictors based on observed k-record values for the cases when the future sample size is fixed and when it is random. Several Bayesian prediction intervals are derived. Finally, the results of a simulation study and a numerical example are presented for illustrating all the inferential procedures developed here.

4 July 2022 in Mathematical Problems in Engineering
Verified
Journal Article
Open access
PDF file
MAM. M. Amein
M. M. Amein
MEM. El-Saady
M. El-Saady
MSMansour Shrahili
Mansour Shrahili
ASAhmad shafay
Ahmad shafay
The topic of estimating the parameters of Gompertz distribution using an adaptive Type-II progressively censored data are described in this paper. The unknown parameters, the reliability, and the hazard functions are estimated using maximum likelihood and Bayesian estimation methods. The approximate confidence intervals of them are then determined. Furthermore, the Markov chain Monte Carlo approach is used to perform a Bayesian estimate procedure and compute the credible intervals. Finally, a Monte Carlo simulation study is done to assess the performance of the two estimating methods, and a numerical example with real data is shown to demonstrate the procedures’ utility.