Methods We conducted a cohort study of 724 603 women aged 40 to 79 years with 2 506 732 mammograms participating in the Breast Cancer Surveillance Consortium from 1995 to 2009. Incident epithelial ovarian cancer was diagnosed in 1373 women. We used partly conditional Cox regression to estimate the association between breast density and 5-year risk of incident epithelial ovarian cancer overall a...

JOSEPH F. Ross, M.D., Editor

JOSEPH F. Ross, M.D., Editor

We describe a full maximum-likelihood fitting method of the popular single-factor Vasicek and Cox–Ingersoll–Ross models and carry this out for term-structure data from the UK and US. This method contrasts with the usual practice of performing a day-by-day fit. We also compare the results with some more crude econometric analyses on the same data sets. © 2000 Elsevier Science B.V. All rights res...

In contrast to the Kaplan-Meier method, Cox proportional hazards regression can provide an effect estimate by quantifying the difference in survival between patient groups and can adjust for confounding effects of other variables. The purpose of this article is to explain the basic concepts of the Cox regression method, and to provide some guidance regarding the presentation of the results. Cop...

JOSEPH F. Ross, M.D., Editor

Often in medical studies of time to an event, the treatment effect is not constant over time. In the context of Cox regression modeling, the most frequent solution is to apply a model that assumes the treatment effect is either piecewise constant or varies smoothly over time, i.e., the Cox nonproportional hazards model. This approach has at least two major limitations. First, it is generally di...