排序方式: 共有14条查询结果,搜索用时 31 毫秒
1.
We analyze left-truncated and right-censored data using Cox proportional hazard models with long-term survivors. The estimators of covariate coefficients and the long-term survivor proportion are obtained by the partial likelihood method, and their asymptotic properties are also established. Simulation studies demonstrate the performance of the proposed estimators, and an application to a real dataset is provided. 相似文献
2.
A. Guilloux 《Mathematical Methods of Statistics》2007,16(3):202-216
In a population of individuals, where the random variable (r.v.) σ denotes the birth time and X the lifetime, we consider the case, where an individual can be observed only if its life-line
(σ, X) = {(σ + y, y), 0 ≤ y ≤ X} intersects a given Borel set S in ℝ × ℝ+. Denoting by σ
S and X
S the birth time and lifetime for the observed individuals, we point out that the distribution function (d.f.) F
S of the r.v. X
S suffers from a selection bias in the sense that F
S = ∝ w d F/μ
S, where w and μ
S depend only on the distribution of σ and on F, the d.f. of X. Assuming in addition that the r.v. X
S is randomly right-censored as soon as the individual is selected, we construct a productlimit estimator
for the d.f. F
S and a nonparametric estimator ŵ for the weight function w. We prove a consistency result for ŵ and a weak convergence result for
. We establish in addition an exponential bound for
.
相似文献
3.
《Operations Research Letters》2022,50(5):476-483
Recently, many researchers focused on modeling non-monotonic hazard functions such as bath-tube and hump shapes. However, most of their estimation methods are focused on complete observations. Since reliability data are typically censored and truncated, a general EM algorithm is proposed, which can fit any of those complex hazard functions. The proposed EM algorithm is analyzed by fitting well-known 4-parameter hazard functions, where its performance is compared by their specific direct methods through extensive Monte Carlo simulations. 相似文献
4.
5.
??In survival analysis, most existing approaches for analysing
right-censored failure time data assume that the censoring time is independent of the
failure time. However, investigators often face problems involving dependent censoring,
i.e., failure time and censoring time are possibly dependent and they may be censored
one another, especially in clinical trials. Without accounting for such dependence,
survival distributions cannot be estimated consistently. Numerous attempts to model
this dependence have been made. Among them, copula models are of particular interest
because of their simple structure. Proportional hazard model analysis for informative
right-censored data has been discussed in this paper. An Archimedean copula is assumed
for the joint distribution function of failure time and censoring time variables. Under
the conditions of identifiability of the parameter of the Archimedean copula, the maximum
likelihood estimators of the parameter of Archimedean copula, the parameters and the
cumulative hazard function of PH model are worked out. Extensive simulation studies show
that the feasibility of the proposed method and the consistency of the estimators. 相似文献
6.
《Operations Research Letters》2020,48(3):233-239
Phase-type distribution allows approximation of non-Markovian models, which permits to analyze complex systems under Markovian deterioration. In addition, reliability data is often composed of truncated and censored observations. This paper presents a novel approach that fits a restricted class of discrete phase-type distribution through pre-specified hazard sequence from incomplete observations. Numerical results are shown using Balakrishnan’s mimicked power transformers dataset. Furthermore, it can be used to fit transition probabilities of maintenance optimization’s Markov decision process models from incomplete reliability data. 相似文献
7.
Length-biased data arise in many important fields, including epidemiological cohort studies, cancer screening trials and labor economics. Analysis of such data has attracted much attention in the literature. In this paper we propose a quantile regression approach for analyzing right-censored and length-biased data. We derive an inverse probability weighted estimating equation corresponding to the quantile regression to correct the bias due to length-bias sampling and informative censoring. This method can easily handle informative censoring induced by length-biased sampling. This is an appealing feature of our proposed method since it is generally difficult to obtain unbiased estimates of risk factors in the presence of length-bias and informative censoring. We establish the consistency and asymptotic distribution of the proposed estimator using empirical process techniques. A resampling method is adopted to estimate the variance of the estimator. We conduct simulation studies to evaluate its finite sample performance and use a real data set to illustrate the application of the proposed method. 相似文献
8.
9.
Pao-sheng Shen 《Annals of the Institute of Statistical Mathematics》2009,61(2):461-476
A class of rank-based tests is proposed for the two-sample problem with left-truncated and right-censored data. The class
contains as special cases the extension of log-rank test and Gehan test. The asymptotic distribution theory of the test is
presented. The small-sample performance of the test is investigated under a variety of situations by means of Mone Carlo simulations. 相似文献
10.
In collecting clinical data, data would be censored due to competing risks or patient withdrawal. The statistical inference for censoring data is always based on the assumption that the failure time and censoring time is independent. But in practice the failure time and censoring time are often dependent. Dependent censoring make the job to deal with censoring data more complicated. In this paper, we assume that the joint distribution of the failure time variable and
censoring time variable is a function of their marginal distributions. This function is called a copula. Under prespecified copulas, the maximum likelihood estimators for cox proportional hazards models are worked out. Statistical analysis results are carried by simulations. When dependent censoring happens, the proposed method will do better than the traditional method used in independent situations. Simulation results show that the proposed method can get efficient estimations. 相似文献