• Title/Summary/Keyword: 이변량 경시적 자료

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Estimation of the joint conditional distribution for repeatedly measured bivariate cholesterol data using Gaussian copula (가우시안 코플라를 이용한 반복측정 이변량 자료의 조건부 결합 분포 추정)

  • Kwak, Minjung
    • The Korean Journal of Applied Statistics
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    • v.30 no.2
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    • pp.203-213
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    • 2017
  • We study estimation and inference of joint conditional distributions of bivariate longitudinal outcomes using regression models and copulas. We consider a class of time-varying transformation models and combine the two marginal models using Gaussian copulas to estimate the joint models. Our models and estimation method can be applied in many situations where the conditional mean-based models are inadequate. Gaussian copulas combined with time-varying transformation models may allow convenient and easy-to-interpret modeling for the joint conditional distributions for bivariate longitudinal data. We apply our method to an epidemiological study of repeatedly measured bivariate cholesterol data.

Estimation of the joint conditional distribution for repeatedly measured bivariate cholesterol data using nonparametric copula (비모수적 코플라를 이용한 반복측정 이변량 자료의 조건부 결합 분포 추정)

  • Kwak, Minjung
    • Journal of the Korean Data and Information Science Society
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    • v.27 no.3
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    • pp.689-700
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    • 2016
  • We study estimation and inference of the joint conditional distributions of bivariate longitudinal outcomes using regression models and copulas. For the estimation of marginal models we consider a class of time-varying transformation models and combine the two marginal models using nonparametric empirical copulas. Regression parameters in the transformation model can be obtained as the solution of estimating equations and our models and estimation method can be applied in many situations where the conditional mean-based models are not good enough. Nonparametric copulas combined with time-varying transformation models may allow quite flexible modeling for the joint conditional distributions for bivariate longitudinal data. We apply our method to an epidemiological study of repeatedly measured bivariate cholesterol data.

Joint model of longitudinal data with informative observation time and competing risk (결시적 자료에서 관측 중단을 모형화하기 위해 사용되는 경쟁 위험의 적용과 결합 모형)

  • Kim, Yang-Jin
    • The Korean Journal of Applied Statistics
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    • v.29 no.1
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    • pp.113-122
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    • 2016
  • Longitudinal data often occur in prospective follow-up studies. Joint model for longitudinal data and failure time has been applied on several works. In this paper, we extend it to the case where longitudinal data involve informative observation time process as well as competing risks survival times. We use a likelihood approach and derive an EM algorithm to obtain maximum likelihood estimate of parameters. A suggested joint model allows us to make inferences for three components: longitudinal outcome, observation time process and competing risk failure time. In addition, we can test the association among these components. In this paper, liver cirrhosis patients' data is analyzed. The relationship between prothrombin times measured at irregular visiting times and drop outs is investigated with a joint model.