Youngseuk Cho

Estimation for the Half Logistic Distribution under Progressive Type-II Censoring

In this paper, we derive the approximate maximum likelihood estimators(AMLEs) and maximum likelihood estimator of the scale parameter in a half-logistic distribution based on progressive Type-II censored samples. We compare the proposed estimators in the sense of the mean squared error for various censored samples. We also obtain the approximate maximum likelihood estimators of the reliability function using the proposed estimators. We compare the proposed estimators in the sense of the mean squared error.

Estimation for the Half Logistic Distribution Based on Double Hybrid Censored Samples

Many articles have considered a hybrid censoring scheme, which is a mixture of Type-I and Type-II censoring schemes. We introduce a double hybrid censoring scheme and derive some approximate maximum likelihood estimators(AMLEs) of the scale parameter for the half logistic distribution under the proposed double hybrid censored samples. The scale parameter is estimated by approximate maximum likelihood estimation method using two different Taylor series expansion types. We also obtain the maximum likelihood estimator(MLE) and the least square estimator(LSE) of the scale parameter under the proposed double hybrid censored samples. We compare the proposed estimators in the sense of the mean squared error. The simulation procedure is repeated 10,000 times for the sample size n = 20(10)40 and various censored samples. The performances of the AMLEs and MLE are very similar in all aspects but the MLE and LSE have not a closed-form expression, some numerical method must be employed.

Estimating the Entropy of a Weibull Distribution under Generalized Progressive Hybrid Censoring

Recently, progressive hybrid censoring schemes have become quite popular in a life-testing problem and reliability analysis. However, the limitation of the progressive hybrid censoring scheme is that it cannot be applied when few failures occur before time T. Therefore, a generalized progressive hybrid censoring scheme was introduced. In this paper, the estimation of the entropy of a two-parameter Weibull distribution based on the generalized progressively censored sample has been considered. The Bayes estimators for the entropy of the Weibull distribution based on the symmetric and asymmetric loss functions, such as the squared error, linex and general entropy loss functions, are provided. The Bayes estimators cannot be obtained explicitly, and Lindley’s approximation is used to obtain the Bayes estimators. Simulation experiments are performed to see the effectiveness of the different estimators. Finally, a real dataset has been analyzed for illustrative purposes.

An Estimation of the Entropy for a Double Exponential Distribution Based on Multiply Type-II Censored Samples

In many life-testing and reliability studies, the experimenter might not always obtain complete information on failure times for all experimental units. Multiply Type-II censored sampling arises in a life-testing experiment whenever the experimenter does not observe the failure times of some units placed on a life-test. In this paper, we obtain estimators for the entropy function of a double exponential distribution under multiply Type-II censored samples using the maximum likelihood estimation and the approximate maximum likelihood estimation procedures. We compare the proposed estimators in the sense of the mean squared errors by using Monte Carlo simulation.

An Estimation of the Entropy for a Rayleigh Distribution Based on Doubly-Generalized Type-II Hybrid Censored Samples

In this paper, based on a doubly generalized Type II censored sample, the maximum likelihood estimators (MLEs), the approximate MLE and the Bayes estimator for the entropy of the Rayleigh distribution are derived. We compare the entropy estimators’ root mean squared error (RMSE), bias and Kullback–Leibler divergence values. The simulation procedure is repeated 10,000 times for the sample size n = 10, 20, 40 and 100 and various doubly generalized Type II hybrid censoring schemes. Finally, a real data set has been analyzed for illustrative purposes.

Estimation of the Exponential Distributions based on Multiply Progressive Type II Censored Sample

The maximum likelihood(ML) estimation of the scale parameters of an exponential distribution based on progressive Type II censored samples is given. The sample is multiply censored (some middle observations being censored); however, the ML method does not admit explicit solutions. In this paper, we propose multiply progressive Type II censoring. This paper presents the statistical inference on the scale parameter for the exponential distribution when samples are multiply progressive Type II censoring. The scale parameter is estimated by approximate ML methods that use two different Taylor series expansion types (AMLEI, AMLEII). We also obtain the maximum likelihood estimator(MLE) of the scale parameter under the proposed multiply progressive Type II censored samples. We compare the estimators in the sense of the mean square error(MSE). The simulation procedure is repeated 10,000 times for the sample size n = 20 and 40 and various censored schemes. The AMLEII is better than MLE and AMLEI in the sense of the MSE.

Inference Based on Generalized Doubly Type-II Hybrid Censored Sample from a Half Logistic Distribution

Abstract Chandrasekar et al. (2004) introduced a generalized Type-II hybrid censoring. In this paper, we proposegeneralized doubly Type-II hybrid censoring. In addition, this paper presents the statistical inference on the scaleparameter ˙for the half logistic distribution when samples are generalized doubly Type-II hybrid censoring. Theapproximate maximum likelihood(AMLE) method is developed to estimate the unknown parameter. The scaleparameter ˙is estimated by the AMLE method using two di erent Taylor series expansion types. We comparethe AMLEs in the sense of the mean square error(MSE). The simulation procedure is repeated 10,000 times forthe sample size n = 20;30;40 and various censored samples. The AMLE I is better than AMLE II in the sense ofthe MSE.Keywords: Approximate maximum likelihood estimator, generalized doubly Type-II hybrid cen-sored sample, half logistic distribution. 1. Introduction Consider a life testing experiment in which nunits are put on test. Assume that the life times of nunitsare independent and identically distributed(i.i.d) as half logistic distribution with probability densityfunction(pdf)f

Bayesian and maximum likelihood estimations of the inverted exponentiated half logistic distribution under progressive Type II censoring

ABSTRACT In this paper, the estimation of parameters, reliability and hazard functions of a inverted exponentiated half logistic distribution (IEHLD) from progressive Type II censored data has been considered. The Bayes estimates for progressive Type II censored IEHLD under asymmetric and symmetric loss functions such as squared error, general entropy and linex loss function are provided. The Bayes estimates for progressive Type II censored IEHLD parameters, reliability and hazard functions are also obtained under the balanced loss functions. However, the Bayes estimates cannot be obtained explicitly, Lindley approximation method and importance sampling procedure are considered to obtain the Bayes estimates. Furthermore, the asymptotic normality of the maximum likelihood estimates is used to obtain the approximate confidence intervals. The highest posterior density credible intervals of the parameters based on importance sampling procedure are computed. Simulations are performed to see the performance of the proposed estimates. For illustrative purposes, two data sets have been analyzed.

SNP analysis of genes related to cholesterol metabolism and associated with late-onset Alzheimer’s disease

Late onset Alzheimer’s disease (LOAD) is the most common type of dementia and is characterized by impaired cholesterol homeostasis. Genome-wide association studies (GWAS) have shown that APOE, TOMM40, CLU, SORL1, PICALM, and BIN1 are related to cholesterol metabolism. To characterize the association between single-nucleotide polymorphisms (SNPs) and LOAD, we sequenced the SNP regions of the identified genes in a total of 11 LOAD cases and 12 healthy case controls in the Korean population. The SNP data showed a relatively high frequency in LOAD samples compared to the control samples. LOAD samples showed an average of 2.9 SNPs, whereas normal controls showed an average of 1.5 SNPs in the genes. Taken together, six genes associated with cholesterol metabolism using SNP analysis have shown frequent genetic variations in LOAD.

Compliance of Screening Implementation-related Factors and after Treatment of Cervical Precancerous Lesions

The purpose of this study was to investigate the compliance rate and related factors of follow-up after treatment for premalignant lesions of the uterine cervix. Data were collected retrospectively from medical records of 362 women who had received treatment for premalignant lesions of uterine cervix from 2009 to 2013 at P hospital in Y city, Korea. Participants were grouped into three groups by their compliance rate of follow-up: high 32.0%, moderate 45.3%, low 22.7%, respectively. The compliance rate of follow-up was statistically significant by education level and hormone therapy. Based on the results, systematic education about importance of follow-up will helpful to improve the compliance after treatment for premalignant Received (July 09, 2015), Review Request(July 10, 2015), Review Result(July 27, 2015) Accepted(August 19, 2015), Published(October 31, 2015) 626-815 Yangsan Busan National University Hospital, 50 Geumo-ro, Mulgeum-eup, Yangsan-si, Gyeongsangnam-do, Korea email: roseeui@hanmail.net (Corresponding Author) 626-870 College of Nursing, 49 Busandaehak-ro, Mulgeum-eup, Yangsan-si, Gyeongsangnam-do, Korea. email: jyha1028@pusan.ac.kr 626-815 Yangsan Busan National University Hospital, 50 Geumo-ro, Mulgeum-eup, Yangsan-si, Gyeongsangnam-do, Korea email: mixbluemix@naver.com 609-735 College of Natural Sciences, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan, Korea. email: choys@pusan.ac.kr Compliance of screening implementation-related factors and after treatment of cervical precancerous lesions Copyright c 2015 HSST 178 lesions of uterine cervix among women.