Commentary: Understanding limitations

Invited commentary: understanding bias amplification.

In choosing covariates for adjustment or inclusion in propensity score analysis, researchers must weigh the benefit of reducing confounding bias carried by those covariates against the risk of amplifying residual bias carried by unmeasured confounders. The latter is characteristic of covariates that act like instrumental variables-that is, variables that are more strongly associated with the ex...

Commentary: Understanding the Flexner report.

Invited Commentary Invited Commentary: Understanding the Role of Sleep

Chronic sleep deprivation is increasingly entertained as a novel risk factor for obesity. However, the vast majority of studies on this topic have relied on unvalidated subjective measures of habitual sleep habits. The accompanying paper by Lauderdale et al. (Am J Epidemiol. 2009;170(7):805–813) presents the first longitudinal analysis of the relation between sleep duration and weight change by...

Understanding bandwidth limitations in robot force control

Commentary: Understanding practical lot quality assurance sampling.

Lot Quality Assurance Sampling (LQAS) is a statistical method emanating from the brilliant work of Dodge and Romig, which, together with that of Shewhart, developed into what is known today as Statistical Quality Control. Since the 1980s, LQAS has transitioned into the health sciences and has gained considerable appeal in a wide range of applications. We disagree with the statement in the obloq...