I first wish to thank Dr Austin for an important paper on the use of propensity score methods in practice. It follows a series of papers by Dr Austin highlighting issues that applied researchers face in using propensity score methods—an area of research that deserves more attention. As Dr Austin shows, there has been considerable misuse and misunderstanding of propensity score methods. Papers s...

BACKGROUND Few models of how community mobilisation works have been elaborated in the scientific literature, and evaluation of the impact of these programmes on HIV and other health outcomes is extremely limited. Avahan, the India AIDS Initiative, has been implementing community mobilisation as part of its prevention programming with groups of high-risk individuals across six states since 2005....

Propensity-score matching is increasingly being used to estimate the effects of treatments using observational data. In many-to-one (M:1) matching on the propensity score, M untreated subjects are matched to each treated subject using the propensity score. The authors used Monte Carlo simulations to examine the effect of the choice of M on the statistical performance of matched estimators. They...

In individually randomised controlled trials, adjustment for baseline characteristics is often undertaken to increase precision of the treatment effect estimate. This is usually performed using covariate adjustment in outcome regression models. An alternative method of adjustment is to use inverse probability-of-treatment weighting (IPTW), on the basis of estimated propensity scores. We calcula...

We first define some notation. Let Y denote the response of interest and X denote a p-dimensional vector of covariates. Let T denote a binary indicator of treatment exposure: T = 1 if treated, T = 0 if control. (Yi,Xi, Ti), i = 1, . . . , n, is a random sample from (Y,X, T ). We further define Y (1) as the potential outcome if the subject were treated and Y (0) as the potential outcome if the s...

The propensity score is the probability of treatment assignment conditional on observed baseline characteristics. The propensity score allows one to design and analyze an observational (nonrandomized) study so that it mimics some of the particular characteristics of a randomized controlled trial. In particular, the propensity score is a balancing score: conditional on the propensity score, the ...

OBJECTIVES Caring for grandchildren is a common and normative experience for many Chinese grandparents. This study investigates the influence of child care provision on older adults' health trajectories in China. METHOD Using data from the China Health and Nutrition Survey (1991, 1993, 1997, 2000, 2004, and 2006), we apply growth curve models to examine the effect of living arrangements and i...

In cancer observational studies, differences between groups on confounding variables may have a significant effect on results when examining health outcomes. This study demonstrates the utility of propensity score matching to balance a non-cancer and cancer cohort of older adults on multiple relevant covariates. This approach matches cases to controls on a single indicator, the propensity score...