We present nine methods to compute an adjusted relative risk (RR). These methods evolved over the past 25 years (1985–2010) via SAS/STAT® procedures: FREQ, GENMOD, LOGISTIC, and PHREG. We also compare the strengths and limitations of these methods, using an observational cohort study for illustration. INTRODUCTION The relative risk (RR) is a common measure of the effect of treatment or exposure...

We extend the Tarone and Ware scheme of weighted log-rank tests to cover the associated weighted Mantel-Haenszel estimators of relative risk. Weighting functions previously employed are critically reviewed. The notion of an average hazard ratio is defined and its connection to the effect size measure P(Y > X) is emphasized. The connection makes estimation of P(Y > X) possible also under censori...

The aim of this retrospective study was to identify general health problems as potential predisposing factors for hypodontia in a population of Japanese orthodontic patients. The study included 3683 individuals (1312 males and 2371 females, 13-42 years of age; mean, 23 years 7 months). Dental pantomograms (DPTs) were used to diagnose hypodontia. Health histories were obtained through a question...

This was a retrospective review of normally formed perinatal deaths among 176,620 births at the National Maternity Hospital (1984-2007). Prelabor stillbirths were categorised by presumed cause of death including unexplained, intrauterine growth retardation (IUGR), placental abruption, red cell alloimmunisation (RCA) and deaths related to prematurity. Peripartum deaths included intrapartum and f...

In high-dimensional settings, where the number of features p is much larger than the number of samples n, methods that systematically examine arbitrary combinations of features have only recently begun to be explored. However, none of the current methods is able to assess the association between feature combinations and a target variable while conditioning on a categorical covariate. As a resul...

PURPOSE To evaluate the clinical performance of C-Posts, AEstheti Posts and AEstheti Plus Posts after a period of clinical service ranging from 1-6 yrs. MATERIALS AND METHODS 1,304 posts were included in the study: 840 Composiposts, 215 AEstheti posts and 249 AEstheti Plus posts were placed into endodontically treated teeth. Four combinations of bonding/luting materials were used. The patient...

Nathan Mantel's many contributions to epidemiology grew out of his role as a statistical consultant and collaborator. His abilities to understand scientific issues, appreciate their subtleties, and produce simple, compelling analyses were remarkable. Several of the procedures he developed to meet consulting needs remain widely used by statisticians and other researchers. Examples are presented ...

Thirty publications on the effectiveness of prophylactic antiepileptic drugs (AEDs) with supratentorial craniotomies were reviewed (1980-1995). After a first selection, six controlled studies remained (11 publications). These six were evaluated according to previously defined methodological criteria. The criteria were divided into three main categories: (1) internal validity, (2) proper and rel...

In traditional (cumulative-incidence) case-control studies, the exposure odds ratio can be used as an estimator of the risk ratio only when the disease under study is rare. The case-cohort study is a recently developed useful modification of the case-control study. This design allows direct estimation of the risk ratio from a fixed cohort, but does not require any rare-disease assumption. This ...