Muhammed Qamarul İslam

Department of Statistics
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Estimation and hypothesis testing in multivariate linear regression models under non normality
İslam, Muhammed Qamarul (Informa UK Limited, 2017-01-01)
This paper discusses the problem of statistical inference in multivariate linear regression models when the errors involved are non normally distributed. We consider multivariate t-distribution, a fat-tailed distribution, ...
A Single Phase AC-AC Boost Converter With Improved Input Power Factor and THD
Kabir, Md. Ashfanoor; Abedin, Amina Hasan; Mustafiz, Rubiya Binta; İslam, Muhammed Qamarul; Choudhury, M. A. (2011-09-10)
A new circuit is proposed for single phase AC-AC conversion using Boost topology. Input Power factor, input current Total Harmonic Distortion (THD) and efficiency of the circuit are examined for the proposed circuit for di...
Multiple linear regression model with stochastic design variables
İslam, Muhammed Qamarul; Tiku, Moti L. (Informa UK Limited, 2010-01-01)
In a simple multiple linear regression model, the design variables have traditionally been assumed to be non-stochastic. In numerous real-life situations, however, they are stochastic and non-normal. Estimators of paramete...
Mahalanobis distance under non-normality
Tiku, Moti L.; İslam, Muhammed Qamarul; Qumsiyeh, Sahar B. (Informa UK Limited, 2010-01-01)
We give a novel estimator of Mahalanobis distance D2 between two non-normal populations. We show that it is enormously more efficient and robust than the traditional estimator based on least squares estimators. We give a t...
Estimation in bivariate nonnormal distributions with stochastic variance functions
Tiku, Moti L.; İslam, Muhammed Qamarul; SAZAK, HAKAN SAVAŞ (Elsevier BV, 2008-01-01)
Data sets in numerous areas of application can be modelled by symmetric bivariate nonnormal distributions. Estimation of parameters in such situations is considered when the mean and variance of one variable is a linear an...
Regression analysis with a dtochastic design variable
Sazak, HS; Tiku, ML; İslam, Muhammed Qamarul (Wiley, 2006-04-01)
In regression models, the design variable has primarily been treated as a nonstochastic variable. In numerous situations, however, the design variable is stochastic. The estimation and hypothesis testing problems in such s...
Sample design and allocation for random digit dialling
Ayhan, HO; İslam, Muhammed Qamarul (Springer Science and Business Media LLC, 2005-10-01)
Sample design and sample allocation methods are developed for random digit dialling in household telephone surveys. The proposed method is based on a two-way stratification of telephone numbers. A weighted probability prop...
Multiple linear regression model under nonnormality
İslam, Muhammed Qamarul; Tiku, ML (Informa UK Limited, 2004-10-01)
We consider multiple linear regression models under nonnormality. We derive modified maximum likelihood estimators (MMLEs) of the parameters and show that they are efficient and robust. We show that the least squares esima...
Nonnormal regression. I. Skew distributions
İslam, Muhammed Qamarul; Tiku, ML; Yildirim, F (2001-01-01)
In a linear regression model of the type y = thetaX + e, it is often assumed that the random error e is normally distributed. In numerous situations, e.g., when y measures life times or reaction times, e typically has a sk...
Nonnormal regression. II. Symmetric distributions
Tiku, ML; İslam, Muhammed Qamarul; Kestel, Sevtap Ayşe (2001-01-01)
Salient features of a family of short-tailed symmetric distributions, introduced recently by Tiku and Vaughan [1], are enunciated. Assuming the error distribution to be one of this family, the methodology of modified likel...
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