scholarly journals Estimating effect of environmental contaminants on women's subfecundity for the MoBa study data with an outcome-dependent sampling scheme

Biostatistics ◽  
2014 ◽  
Vol 15 (4) ◽  
pp. 636-650 ◽  
Author(s):  
Jieli Ding ◽  
Haibo Zhou ◽  
Yanyan Liu ◽  
Jianwen Cai ◽  
Matthew P. Longnecker
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Failure Time ◽  
Asymptotic Properties ◽  
Likelihood Estimation ◽  
Small Sample ◽  
Environmental Study ◽  
Time Data ◽  
Model Framework ◽  
Data Set

Abstract Motivated by the need from our on-going environmental study in the Norwegian Mother and Child Cohort (MoBa) study, we consider an outcome-dependent sampling (ODS) scheme for failure-time data with censoring. Like the case-cohort design, the ODS design enriches the observed sample by selectively including certain failure subjects. We present an estimated maximum semiparametric empirical likelihood estimation (EMSELE) under the proportional hazards model framework. The asymptotic properties of the proposed estimator were derived. Simulation studies were conducted to evaluate the small-sample performance of our proposed method. Our analyses show that the proposed estimator and design is more efficient than the current default approach and other competing approaches. Applying the proposed approach with the data set from the MoBa study, we found a significant effect of an environmental contaminant on fecundability.

A unified approach to variable selection for Cox’s proportional hazards model with interval-censored failure time data

2021 ◽  
pp. 096228022110092
Author(s):  
Mingyue Du ◽  
Hui Zhao ◽  
Jianguo Sun
Keyword(s):  
Variable Selection ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Failure Time ◽  
Significant Feature ◽  
Failure Time Data ◽  
Time Data ◽  
Hazards Model ◽  
Interval Censored ◽  
Cox's Proportional Hazards Model

Cox’s proportional hazards model is the most commonly used model for regression analysis of failure time data and some methods have been developed for its variable selection under different situations. In this paper, we consider a general type of failure time data, case K interval-censored data, that include all of other types discussed as special cases, and propose a unified penalized variable selection procedure. In addition to its generality, another significant feature of the proposed approach is that unlike all of the existing variable selection methods for failure time data, the proposed approach allows dependent censoring, which can occur quite often and could lead to biased or misleading conclusions if not taken into account. For the implementation, a coordinate descent algorithm is developed and the oracle property of the proposed method is established. The numerical studies indicate that the proposed approach works well for practical situations and it is applied to a set of real data arising from Alzheimer’s Disease Neuroimaging Initiative study that motivated this study.

scholarly journals An Inference-based Prognostic Framework for Health Management of Automotive Systems

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Chaitanya Sankavaram ◽  
Anuradha Kodali ◽  
Krishna Pattipati ◽  
Satnam Singh ◽  
Yilu Zhang ◽  
...  
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Failure Time ◽  
Remaining Useful Life ◽  
Survival Functions ◽  
Time Data ◽  
Automotive Systems ◽  
Multiple Fault Diagnosis ◽  
Hazards Model ◽  
Useful Life

This paper presents a unified data-driven prognostic framework that combines failure time data, static parameter data and dynamic time-series data. The framework employs proportional hazards model and a soft dynamic multiple fault diagnosis algorithm for inferring the degraded state trajectories of components and to estimate their remaining useful life times. The framework takes into account the cross-subsystem fault propagation, a case prevalent in any networked and embedded system. The key idea is to use Cox proportional hazards model to estimate the survival functions of error codes and symptoms (probabilistic test outcomes/prognostic indicators) from failure time data and static parameter data, and use them to infer the survival functions of components via soft dynamic multiple fault diagnosis algorithm. The average remaining useful life and its higher-order central moments (e.g., variance, skewness, kurtosis) can be estimated from these component survival functions. The framework is demonstrated on datasets derived from two automotive systems, namely hybrid electric vehicle regenerative braking system, and an electronic throttle control subsystem simulator. Although the proposed framework is validated on automotive systems, it has the potential to be applicable to a wide variety of systems, ranging from aerospace systems to buildings to power grids.

Some Reliability Models for Analyzing the Effect of Operating Conditions

1997 ◽  
Vol 04 (02) ◽  
pp. 133-148 ◽  
Author(s):  
Dhananjay Kumar ◽  
Ulf Westberg
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Failure Time ◽  
Operating Conditions ◽  
Accelerated Failure Time ◽  
Data Set ◽  
Proportional Hazards Models ◽  
Reliability Models ◽  
Accelerated Failure Time Models ◽  
Accelerated Failure

Basic approaches of some of the reliability models available for analyzing the effect of operating conditions (or covariates) on the lifetime of a system are shortly discussed, and a general guideline for how to select an appropriate model for a given data set is provided. Some of the models have theoretical and computational difficulties which make them difficult to apply. Models that appear to be suitable for practical applications can broadly be classified as the class of proportional hazards models and the class of accelerated failure time models. In the class of proportional hazards models, e.g. the proportional hazards model and the proportional odds model, the effect of the covariates is assumed to act multiplicatively on the hazard rate or its transformations. In the class of accelerated failure time models, e.g. the parametric regression models, the effect of the covariates is assumed to act multiplicatively on the failure time or its transformations. Models from the proportional hazards family appear to be the better ones for analyzing the effect of the covariates due to the method used for estimating the parameters of these models.

scholarly journals Efficient sparse estimation on interval-censored data with approximated L0 norm: Application to child mortality

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249359
Author(s):  
Yan Chen ◽  
Yulu Zhao
Keyword(s):  
Child Mortality ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Failure Time ◽  
Estimation Method ◽  
Information Criterion ◽  
Great Accuracy ◽  
Time Data ◽  
Sparse Estimation ◽  
Interval Censored

A novel penalty for the proportional hazards model under the interval-censored failure time data structure is discussed, with which the subject of variable selection is rarely studied. The penalty comes from an idea to approximate some information criterion, e.g., the BIC or AIC, and the core process is to smooth the ℓ0 norm. Compared with usual regularization methods, the proposed approach is free of heavily time-consuming hyperparameter tuning. The efficiency is further improved by fitting the model and selecting variables in one step. To achieve this, sieve likelihood is introduced, which simultaneously estimates the coefficients and baseline cumulative hazards function. Furthermore, it is shown that the three desired properties for penalties, i.e., continuity, sparsity, and unbiasedness, are all guaranteed. Numerical results show that the proposed sparse estimation method is of great accuracy and efficiency. Finally, the method is used on data of Nigerian children and the key factors that have effects on child mortality are found.

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