• 제목/요약/키워드: Censored Data

검색결과 405건 처리시간 0.026초

Analyzing Clustered and Interval-Censored Data based on the Semiparametric Frailty Model

  • Kim, Jin-Heum;Kim, Youn-Nam
    • 응용통계연구
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    • 제25권5호
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    • pp.707-718
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    • 2012
  • We propose a semi-parametric model to analyze clustered and interval-censored data; in addition, we plugged-in a gamma frailty to the model to measure the association of members within the same cluster. We propose an estimation procedure based on EM algorithm. Simulation results showed that our estimation procedure may result in unbiased estimates. The standard error is smaller than expected and provides conservative results to estimate the coverage rate; however, this trend gradually disappeared as the number of members in the same cluster increased. In addition, our proposed method was illustrated with data taken from diabetic retinopathy studies to evaluate the effectiveness of laser photocoagulation in delaying or preventing the onset of blindness in individuals with diabetic retinopathy.

이변량 임의 중단된 이변량지수 모형에 대한 추론 (Inference for Bivariate Exponential Model with Bivariate Random Censored Data)

  • 조장식;신임희
    • Journal of the Korean Data and Information Science Society
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    • 제10권1호
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    • pp.37-45
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    • 1999
  • 본 논문에서는 Marshall-Olkin의 이변량 지수모형을 따르는 두 부품의 수명들이 이변량 임의 중단된 자료로 관찰되는 경우를 생각한다. 이 경우 모수와 시스템 신뢰도에 대한 최우추정량을 구하고 근사적 정규성을 이용하여 두 부품의 수명에 대한 동일성 및 독립성 검정법을 제안한다. 그리고 모의실험을 통하여 제안된 추정량들과 검정법들의 유의확률을 계산한다.

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Estimation for Block and Basu Model under System Level Life Testing

  • Hwang, In-Sob;Cho, Jang-Sik;Cho, Kil-Ho
    • Journal of the Korean Data and Information Science Society
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    • 제18권3호
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    • pp.637-644
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    • 2007
  • We consider a life testing experiment in which several two component shared parallel system are put on test, and the test is terminated at a pre-designed experiment. The bivariate data obtained from such a system level life testing can be classified into three cases: (1) the case of failed two components with known failure times, (2) the case of one censored component and the other failed component of which the failure time might be known or unknown, (3) the case of censored two components. In this paper, the maximum likelihood estimators of parameters for Block and Basu bivariate exponential model under above censoring scheme are obtained and the results of comparative studies are presented.

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Tests for Exponentiality Against Harmonic New Better Than Used in Expectation Property of Life Distributions

  • Al-Ruzaiza, A.S.
    • International Journal of Reliability and Applications
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    • 제4권4호
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    • pp.171-181
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    • 2003
  • This paper proposes a U-test statistic for the problem of testing that a life distribution is exponential against the alternative that it is harmonic new better (worse) than used in expectation upper tail HNBUET (HNWUET), but not exponential on complete data. Selected critical values are tabulated for sample sizes n =5(1)60. The asymptotic normality of the statistic is proved and a comparison is made of the asymptotic efficiency between the statistic and other statistics. The power of the test is studied by simulation. A test for HNBUET in the case of randomly right-censored data is also considered. An application of the proposed test statistic in medical sciences is given.

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Use of Lèvy distribution to analyze longitudinal data with asymmetric distribution and presence of left censored data

  • Achcar, Jorge A.;Coelho-Barros, Emilio A.;Cuevas, Jose Rafael Tovar;Mazucheli, Josmar
    • Communications for Statistical Applications and Methods
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    • 제25권1호
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    • pp.43-60
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    • 2018
  • This paper considers the use of classical and Bayesian inference methods to analyze data generated by variables whose natural behavior can be modeled using asymmetric distributions in the presence of left censoring. Our approach used a $L{\grave{e}}vy$ distribution in the presence of left censored data and covariates. This distribution could be a good alternative to model data with asymmetric behavior in many applications as lifetime data for instance, especially in engineering applications and health research, when some observations are large in comparison to other ones and standard distributions commonly used to model asymmetry data like the exponential, Weibull or log-logistic are not appropriate to be fitted by the data. Inferences for the parameters of the proposed model under a classical inference approach are obtained using a maximum likelihood estimators (MLEs) approach and usual asymptotical normality for MLEs based on the Fisher information measure. Under a Bayesian approach, the posterior summaries of interest are obtained using standard Markov chain Monte Carlo simulation methods and available software like SAS. A numerical illustration is presented considering data of thyroglobulin levels present in a group of individuals with differentiated cancer of thyroid.

이중구간중도절단된 생존자료의 생존함수 비교를 위한 검정: 한국인 암 예방연구 중 당뇨병에의 응용 (Comparing Survival Functions with Doubly Interval-Censored Data: An Application to Diabetes Surveyed by Korean Cancer Prevention Study)

  • 지선하;남정모;김진흠
    • 응용통계연구
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    • 제22권3호
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    • pp.595-606
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    • 2009
  • 이중구간중도절단된 자료의 생존함수를 비교하기 위한 두 검정법을 소개하고 한국인 암 예방연구 (Jee 등, 2005) 자료에 적용하여 당뇨병 잠복시간의 분포를 성별과 연령에 따라 비교하였다. Kim 등 (2006)의 검정법을 이중구간중도절단된 자료로 확장한 검정법은 위험집합의 크기에만 의존하는 가중값을 사용하기 때문에 대용량 자료의 분석에서 Sun (2006)의 검정법보다 계산 시간을 대폭 줄일 수 있으며, 이산형 생존자료뿐만 아니라 연속형 생존자료에도 적용가능한 장점이 있다. 당뇨병의 잠복시간이 성별에 따라 매우 유의하게 달랐으며 여자의 잠복시간이 남자보다 긴 것으로 나타났다. 4개 연령그룹 간 당뇨병의 잠복시간도 성별에 관계 없이 매우 유의하게 달랐으며 여자의 경우가 남자의 경우보다 그 차이가 훨씬 더 유의했다. 한편, 소표본 모의실험을 통해 제안한 검정법과 Sun (2006)의 검정법의 검정력을 비교하였으며 제안한 검정법의 검정력이 Sun (2006)의 검정법보다 더 좋은 것으로 나타났다.

제2종(第2種) 중단(中斷) 자료(資料)에서 두 모수지수분포(母數指數分布)의 베이지안 추정(推定) (Bayesian Estimations for the Two-parameter Exponential Model under the Type-II Censoring)

  • 김헌주;윤용화;고정환
    • Journal of the Korean Data and Information Science Society
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    • 제4권
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    • pp.65-74
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    • 1993
  • Suppose that we have two populations(or systems), say ${\Pi}_{1}\;and\;{\Pi}_{2}$, to be tested. A random sample of size n from each population is taken and the test for each system will be terminated when the first r failures among n random samples are observed. This kind of test is caned the type-II censored (or item-censored) testing without replacement. Under this scheme we consider the problem of estimating the unknown parameters of interests and the reliability for a given time t for each population.

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INDEPENDENCE TEST FOR BIVARIATE CENSORED DATA UNDER UNIVARIATE CENSORSHIP

  • Kim, Jin-Heum;Cai, Jian-Wen
    • Journal of the Korean Statistical Society
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    • 제32권2호
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    • pp.163-174
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    • 2003
  • We propose a test for independence of bivariate censored data under univariate censorship. To do this, we first introduce a process defined by the difference between bivariate survival function estimator proposed by Lin and Ying (1993) and the product of the product-limit estimators (Kaplan and Meier, 1958) for the marginal survival functions, and derive its asymptotic properties under the null hypothesis of independence. We propose a Cramer-von Mises-type test procedure based on the process . We conduct simulation studies to investigate the finite-sample performance of the proposed test and illustrate the proposed test with a real example.

Application of Convariance Process to Tests for Censored Paired Data

  • Jeong, Gyu-Jin
    • Communications for Statistical Applications and Methods
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    • 제6권2호
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    • pp.565-584
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    • 1999
  • the covariance process of two martingales provides a useful tool to capture the dependence structure for paired censored data. in this paper it is applied to modify the variances of weighted logrank tests in order to take account of dependence between paired subjects. In the process of modification a 'variance correction term' is introduced. Some variance estimators based on separate samples are considered together. Performance of the estimators are compared through simulation studies. Several independence tests for bivariate sruvival date are also proposed which are naturally reduced from the weighted logrank tests accomodating dependence structure. Simulation studies are carried out to compare the independence tests. Both the weighted logrank tests and the independence tests are illustrated by an example.

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Bayesian Approach to the Prediction in the Censored Sample from Rayleigh Population

  • Ko, Jeong-Hwan;Kim, Young-Hoon;Kang, Sang-Gil
    • Journal of the Korean Data and Information Science Society
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    • 제8권1호
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    • pp.71-77
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    • 1997
  • S independent sample 0,1,2, $\cdots$, s-1 (or stages 0,1,2, $\cdots$, s-1) are available from the Raleigh population. Procedure for predicting any order statistic in the $(s+1)^{th}$ sample is developed by obtaining the predictive distribution at stage s. Bounds for the sample size at stage S, in order to have the variance at stage S less than that at stage (s-1), are obtained.

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