BACKGROUND It is known that experience of a previous crash is related to incidence of future crashes in a cohort of New Zealand cyclists. This paper investigated if the strength of such association differed by crash involvement propensity and by the need for medical care in the previous crash. METHODS The Taupo Bicycle Study involved 2590 adult cyclists recruited in 2006 and followed over a m...

Studies have revealed that relative poverty is associated with ill health, but the interpretations of this correlation vary. This article asks whether relative poverty among Norwegian adolescents is causally related to poor subjective health, i.e., self-reported somatic and mental symptoms. Data consist of interview responses from a sample of adolescents (N = 510) and their parents, combined wi...

Having combined data on Quebec scientists’ funding and journal publication, this paper tests the effect of having a research chair on the scientists’ performance. The novelty of this paper is to use matching technique to understand whether having a research chair is a real cause for better scientific performance. This method compares two different sets of regressions, which are conducted on dif...

For some time, propensity score (PS) based methods have been frequently applied in the analysis of observational and registry data. The PS is the conditional probability of a certain treatment given patient’s covariates. PS methods are used to eliminate imbalances in baseline covariate distributions between treatment groups and permit to estimate marginal effects. The package nonrandom is a too...

This retrospective cross-sectional paper examines the relationship between maternal smoking during pregnancy and children's behavioural problems at 9 years of age independent of a wide range of possible confounders. The final sample comprised 7,505 nine-year-old school children participating in the first wave of the Growing Up in Ireland study. The children were selected through the Irish natio...

TO THE EDITOR—We appreciate the comments from Decker et al regarding our study [1]. There are now 3 studies reporting comparative effectiveness results for high-dose vs standard-dose influenza vaccine. Decker et al's Sanofi Pasteur ran-domized trial [2] necessarily focused on symptomatic influenza infection as hospitalization with complications of influenza is less common, and comparisons based...

This study uses the Propensity Score Matching to examine the income impact of different credit sources on accessed households in the Northern Mountains of Vietnam. Results show that overall rural credit serves an important role in improving household income with respect to total income, per capita income and nonfarm income. However, different credit affects recipients heterogeneously. Whereas a...

Suppose we are interested in estimating the average causal effect from an observational study. A doubly robust estimator, which is a hybrid of the outcome regression and propensity score weighting, is more robust than estimators obtained by either of them in the sense that, if at least one of the two models holds, the doubly robust estimator is consistent. However, a doubly robust estimator may...

Propensity scores are widely used in cohort studies to improve performance of regression models when considering large numbers of covariates. Another type of summary score, the disease risk score (DRS), which estimates disease probability conditional on nonexposure, has also been suggested. However, little is known about how it compares with propensity scores. Monte Carlo simulations were condu...

OBJECTIVES The propensity score (PS) method is increasingly used to assess treatment effects in nonrandomized trials. Although there are several methods to use the PS for analysis, matching treated and untreated patients by the PS is recommended by most researchers among other reasons because this allows assessing covariate balance before and after matching. Although the standardized difference...