• Journal of the Korean Data and Information Science Society
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• 제15권4호
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• pp.957-963
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• 2004

A new agreement measure for multivariate interval data by different sets of raters is proposed. The proposed approach builds on Um's multivariate extension of Cohen's kappa. The proposed measure is compared with corresponding earlier measures based on Berry and Mielke's approach and Janson and Olsson approach, respectively. Application of the proposed measure is exemplified using hypothetical data set.

• Journal of the Korean Data and Information Science Society
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• 제15권1호
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• pp.263-271
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• 2004

This article presents a new measure of chance-corrected interobserver agreement among multivariate ratings of many observers. Modifying an approach by Berry and Mielke, a new agreement measure is proposed. The important modificaton is to use the volume of simplex composed of data points as the disagreement masure. The proposed measure accounts agreement for multivariate interval observations among many observers. Hypothetical and real-life data sets are analyzed for illustrative purpose.

• Communications for Statistical Applications and Methods
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• 제30권4호
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• pp.389-402
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• 2023

Multivariate or clustered failure time data often occur in many medical, epidemiological, and socio-economic studies when survival data are collected from several research centers. If the data are periodically observed as in a longitudinal study, survival times are often subject to various types of interval-censoring, creating multivariate interval-censored data. Then, the event times of interest may be correlated among individuals who come from the same cluster. In this article, we propose a unified linear regression method for analyzing multivariate interval-censored data. We consider a semiparametric multivariate accelerated failure time model as a statistical analysis tool and develop a generalized Buckley-James method to make inferences by imputing interval-censored observations with their conditional mean values. Since the study population consists of several heterogeneous clusters, where the subjects in the same cluster may be related, we propose a generalized estimating equations approach to accommodate potential dependence in clusters. Our simulation results confirm that the proposed estimator is robust to misspecification of working covariance matrix and statistical efficiency can increase when the working covariance structure is close to the truth. The proposed method is applied to the dataset from a diabetic retinopathy study.

• Journal of the Korean Data and Information Science Society
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• 제4권
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• pp.31-44
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• 1993

Multivariate exponentially weighted moving average (EWMA) control charts for monitoring the variance-covariance matrix are investigated. A variable sampling interval (VSI) feature is considered in these charts. Multivariate EWMA control charts for monitoring the variance-covariance matrix are compared on the basis of their average time to signal (ATS) performances. The numerical results show that multivariate VSI EWMA control charts are more efficient than corrsponding multivariate fixed sampling interval (FSI) EWMA control charts.

• Journal of the Korean Data and Information Science Society
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• 제17권2호
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• pp.529-536
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• 2006

Investigators use either Euclidean distance or volume of a simplex defined composed of data points as agreement index to measure chance-corrected agreement among observers for multivariate interval data. The agreement coefficient proposed by Um(2004) is based on a volume of a simplex and does not depend on the variables' measuring units. We consider a comparison of Um(2004)'s agreement coefficient with others based on two unit-free distance measures, Pearson distance and Mahalanobis distance. Comparison among them is made using hypothetical data set.

• Journal of the Korean Data and Information Science Society
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• 제16권3호
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• pp.621-628
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• 2005

This article addresses the problem of measuring a joint agreement between multiple raters and a standard set of responses. A new agreement measure based on Um's approach is proposed. The proposed agreement measure is used for multivariate interval responses. Comparison is made between the proposed measure and other corresponding agreement measures using hypothetical data set.

• Journal of the Korean Data and Information Science Society
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• 제21권6호
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• pp.999-1008
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• 2010

공정을 모니터링 하기 위한 전통적인 관리도는 표본들 사이의 일정한 추출간격에서 일정한 수의 표본을 취하여 만들어 지는 고정추출율 관리도이다. 본 연구의 목표는 표준적인 고정추출율을 갖는 다변량 관리도에 비하여 성능이 우수한 가변추출간격을 갖는 다변량 관리도를 개발하는데 있다. 대부분의 다변량 관리도에 대한 연구는 공정의 평균벡터를 모니터링 하는데 초점이 맞추어져 있다. 그러나 본 논문에서는 공정의 평균벡터와 분산-공분산을 동시에 모니터링 하기 위한 다변량 관리도를 연구한다. 가변추출간격을 갖는 다변량 슈하르트 관리도에 대하여 연구 하고자 한다.

• Journal of the Korean Data and Information Science Society
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• 제20권4호
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• pp.741-747
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• 2009

Properties of multivariate Shewhart and EWMA (Exponentially Weighted Moving Average) control charts for monitoring variance-covariance matrix of quality variables are investigated. Performances of the proposed charts are evaluated for matched fixed sampling interval (FSI) and variable sampling interval (VSI) charts in terms of average time to signal (ATS) and average number of samples to signal (ANSS). Average number of swiches (ANSW) of the proposed VSI charts are also investigated.

• 한국컴퓨터정보학회논문지
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• 제20권12호
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• pp.169-174
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• 2015

Permutation p-values are provided for the agreement measures for multivariate interval data among many raters. Three agreement measures, Berry and Mielke's measure, Janson and Olsson's measure, and Um's measure are described and compared. Exact and resampling permutation methods are utilized to compute p-values and empirical quantile limits for three measures. Comparisons of p-values demonstrate that resampling permutation methods provide close approximations to exact p-values, and Berry and Mielke's measure and Um's measure show similar performance in terms of measuring agreement.

• Journal of the Korean Data and Information Science Society
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• 제17권3호
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• pp.973-982
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• 2006

Performances of variable sampling interval(VSI) multivariate control charts with accumulate-combine approach for monitoring mean vector of p related quality variables were investigated. Shewhart control chart is also proposed to compare the performances of CUSUM and EWMA charts. Numerical comparisons show that performances of CUSUM and EWMA charts are more efficient than Shewhart chart for small or moderate shifts, and VSI chart is more efficient than fixed sampling interval(FSI) chart. We also found that performances of the CUSUM or EWMA chart with accumulate-combine approach are substantially efficient than those of Shewhart chart.