This paper develops omnibus tests for comparing cause-speciic hazard rates and cumulative incidence functions at speciied covariate levels. Conndence bands for the diierence and the ratio of two conditional cumulative incidence functions are also constructed. The omnibus test is formulated in terms of a test process given by a weighted diierence of estimates of cumulative cause-speciic hazard r...

Objective: To evaluate the duration of exclusive breastfeeding (EBF) and full breastfeeding (FBF) as well as its determinants within a cohort. Methodology: Data were collected in household interviews. The analysis was performed through the estimative of survival curves, using the Kaplan-Meier method. Differences in the curves were evaluated employing the log-rank test. Cox proportional hazards ...

Pesticides are ubiquitous neurotoxicants, and several lines of evidence suggest that exposure may be associated with depression. Epidemiologic evidence has focused largely on organophosphate exposures, while research on other pesticides is limited. We collected detailed pesticide use history from farmers recruited in 1998–2000 in France. Among 567 farmers aged 37–78 years, 83 (14.6%) self-repor...

J Bone Joint Surg [Br] 2007;89-B:1234-8. Received 1 February 2007; Accepted 24 April 2007 We have reviewed the data from our regional Bone Tumour Registry on patients with osteosarcoma diagnosed between 1933 and 2004 in order to investigate the relationship between survival and changes in treatment. There were 184 patients with non-metastatic appendicular osteosarcoma diagnosed at the age of 18...

We consider two approaches for bias evaluation and reduction in the proportional hazards model (PHM) proposed by Cox. The rst one is an analytical approach in which we derive the n ?1 bias term of the maximum partial likelihood estimator. The second approach consists of resampling methods, namely the jackknife and the bootstrap. We compare all methods through a comprehensive set of Monte Carlo ...

Truncated power basis expansions and penalized spline methods are demonstrated for estimating nonlinear exposure-response relationships in the Cox proportional hazards model. R code is provided for fitting models to get point and interval estimates. The method is illustrated using a simulated data set under a known exposure-response relationship and in a data application examining risk of carpa...

lowing 3 groups: any antibiotics; antibiotics for respiratory infections; and antibiotics for urinary tract or skin and soft tissue infections. Asthma diagnosis was defined as having both an asthma diagnosis and receipt of asthma medications. The association between antibiotic exposure and asthmawas investigatedwithmultivariateCox proportional hazard regression models, and a stratified proporti...

For the last thirty years, the rapid growth in information technologies has led to an absolute explosion in the production and diffusion of statistical software. With dropdown menus replacing meticulously written computer code, it now seems that literally anyone can run a three-way analysis of variance, perform generalized statistical tests for a proportional hazards model, or use varimax rotat...

Number of words: 2795 (excluding summary, references and tables) 2 SUMMARY This paper discusses techniques to generate survival times for simulation studies regarding Cox proportional hazards models. In linear regression models, the response variable is directly connected with the considered covariates, the regression coefficients and the simulated random errors. Thus, the response variable can...

The Cox proportional hazards model is the standard tool for relative risk estimation and inference for survival studies. The generalized logrank (GLR) approach (Mehrotra and Roth, 2001) has been proposed as a more efficient alternative to the Cox model when the number of subjects is small and there are no ties in the data. However, ties will result if continuous data are grouped by rounding to ...