This paper introduces nonparametric U-statistics for testing the curvature (e.g., linearity, concavity, or convexity) of an unknown regression function. The U-statistics are based on pairwise slopes in the data. No choice of smoothing parameters is required for the global version of the statistics or their (asymptotic) standard errors, making them simple to compute. The proposed tests are analo...

For right censored data, Efron (1981) has shown that his “simple” and “obvious” methods of bootstrapping are equivalent. We explain why this equivalence no longer holds for truncated data. Wang (1991) generalized Efron’s “obvious” bootstrap method to data that are both left truncated and right censored, under the assumption that C ≥ T and C − T is independent of T , where T and C denote the (ge...

In the United States, annual mortality rates from pulmonary embolism (PE) tended to increase from the 1960s to the mid 1980s, but thereafter began to decrease. In Japan, PE is not yet widespread and there have not been any reports of the time-trend of its mortality rate. The present study calculated the annual age-adjusted and age-specific PE mortality rates for Japanese residents during 1951 t...

OBJECTIVE To determine whether having cesarean section capability in an isolated rural community makes a difference in adverse maternal or perinatal outcomes. DESIGN Retrospective study comparing population-based obstetric outcomes of two rural remote hospitals in northwestern British Columbia. One hospital had cesarean section capability; one did not. SETTING Bella Coola General Hospital (...

We assess the extent to which differences in socio-economic status are associated with racial and ethnic gaps in a fundamental measure of population health: the rate at which infants die. Using micro-level Vital Statistics data from 2000 to 2004 for whites, blacks, Mexicans, Puerto Ricans, Asians, and Native Americans, we first examine how infant mortality and its subcomponents are associated w...

BACKGROUND AND PURPOSE The number of degree-awarding programmes in medical education is steadily increasing. Despite the popularity and extensive investment in these courses, there is little research into their impact. This study investigated the perceived impact of an internationally-renowned postgraduate programme in medical education on health professionals' development as educators. METHO...

KEY FINDINGS Data from the National Vital Statistics System, Mortality •From 2000 through 2014, the age-adjusted rate for chronic obstructive pulmonary disease (COPD)-related deaths decreased 22.5% for men and 3.8% for women aged 25 and over. •Between 2000 and 2014, the COPD-related death rate decreased for both men and women aged 65-84 and for men aged 85 and over. The rate increased for both ...

Teenage childbearing has been the subject of long-standing concern among the public and policy makers. Teenagers who give birth are much more likely to deliver a low birthweight or preterm infant than older women, and their babies are at elevated risk of dying in infancy. The annual public costs associated with teen childbearing have been estimated at $9.1 billion. The U.S. teen birth rate fell...

OBJECTIVES To study the relationships between global self-rated health, reported physical symptoms and depressive symptoms and the receipt of community services by very elderly people, and to examine changes in these variables over time. DESIGN Three-wave study with follow-up at 2.4 and 6 years after first interview. Structured interview, incorporating cognitive examination (Mini-Mental State...