نتایج جستجو برای: stratifi ed cox proportional hazards model

تعداد نتایج: 2242673  

2018
Peter C. Austin

The use of the Cox proportional hazards regression model is widespread. A key assumption of the model is that of proportional hazards. Analysts frequently test the validity of this assumption using statistical significance testing. However, the statistical power of such assessments is frequently unknown. We used Monte Carlo simulations to estimate the statistical power of two different methods ...

Journal: :Lifetime data analysis 2001
W Pan

The accelerated failure time (AFT) model is an important alternative to the Cox proportional hazards model (PHM) in survival analysis. For multivariate failure time data we propose to use frailties to explicitly account for possible correlations (and heterogeneity) among failure times. An EM-like algorithm analogous to that in the frailty model for the Cox model is adapted. Through simulation i...

Journal: :BMC medical research methodology 2016
Patrick Royston Mahesh K B Parmar

BACKGROUND Most randomized controlled trials with a time-to-event outcome are designed assuming proportional hazards (PH) of the treatment effect. The sample size calculation is based on a logrank test. However, non-proportional hazards are increasingly common. At analysis, the estimated hazards ratio with a confidence interval is usually presented. The estimate is often obtained from a Cox PH ...

2015
Jan Bressler Nora Franceschini Ellen W Demerath Thomas H Mosley Aaron R Folsom

Line 54: How is the variant associated with mean telomere length? Is it associated with increased/decreased length? The A allele of rs2736100 was associated with decreased telomere length. This is described in the last paragraph of the Background section. Methods Line 144: Should read “Six SNPs” rather than “Six (6) SNPs”. This error has been corrected. State whether the assumptions of the cox ...

Abolghasemi, Jamile, Hasannezhad , Malihe, Kargarian-Marvasti , Sadegh,

Background and Objectives: This study aimed to investigate the effective factors in the survival/hazard time of Covid-19 patients in three waves of epidemic.   Methods: All 880 Covid-19 patients were included in this prospective cohort study using the census method. Polymerase chain reaction was used to diagnose Covid-19. The survival status of these patients was followed up for 4 months. The...

2008
Lida Gharibvand George Fernandez

ABSTRACT Survival analysis involves the modeling of time-to-event data whereby death or failure is considered an "event". The graphic presentation of Cox proportional hazards model using SAS PHREG is a significant tool which facilitates effective data exploration in survival analysis. The SAS PROC PHREG can generate some of the useful survival analysis plots using the ODS graphics option in ver...

Journal: :Computational Statistics & Data Analysis 2008
Jie Sun Karen A. Kopciuk Xuewen Lu

The Cox proportional hazards (PH) model usually assumes linearity of the covariates on the log hazard function, which may be violated because linearity cannot always be guaranteed. We propose a partially linear single-index proportional hazards regression model, which can model both linear and nonlinear covariate effects on the log hazard in the proportional hazards model. We adopt a polynomial...

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