Matching on the propensity score is widely used to estimate the effect of an exposure in observational studies. However, the quality of the matches can be affected by decisions made during the matching process, particularly the order in which subjects are selected for matching and the maximum permitted difference between matched subjects (the "caliper"). This study used simulations to explore t...

Each year an estimated two million children in the United States repeat a grade. Investing an additional year in the same grade is expected to help a child to acquire the academic skills she lacks. This, in turn, would help her to be successful in higher grades. In spite of its popularity, grade retention remains a highly controversial practice. A majority of researchers find that, for the repe...

OBJECTIVE To determine the association between use of school-based health centers (SBHCs) and school dropout. DESIGN Quasi-experimental longitudinal analysis of a retrospective student cohort, with SBHC use as the independent variable. We statistically controlled for dropout risk and used propensity score regression adjustment to control for several factors associated with SBHC use. SETTING...

The assessment of treatment effects from observational studies may be biased with patients not randomly allocated to the experimental or control group. One way to overcome this conceptual shortcoming in the design of such studies is the use of propensity scores to adjust for differences of the characteristics between patients treated with experimental and control interventions. The propensity s...

BACKGROUND Millennium Development Goal 1 encourages local initiatives for the eradication of extreme poverty. However, monitoring is indispensable to insure that actions performed at higher policy levels attain success. Poverty in rural areas in low- and middle-income countries remains chronic. Nevertheless, a rural area (Cuatro Santos) in northern Nicaragua has made substantial progress toward...

This study uses within-study comparisons to assess the relative importance of covariate choice, unreliability in the measurement of these covariates, and whether regression or various forms of propensity score analysis are used to analyze the outcome data. Two of the within-study comparisons are of the four-arm type, and many more are of the three-arm type. To examine unreliability, simulations...

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...

* This is the third chapter of a draft book manuscript, " Why Adjudicate? Enforcing Trade Rules. " The full manuscript is available upon request. [email protected].