Assessing bias: the importance of considering confounding

When a difference in an outcome (eg, pain) between exposures (eg, treatment groups) is observed, one needs to consider whether the effect is truly because of exposure or if alternate explanations are possible. As we discussed in the previous issue of EBSJ, to evaluate the validity of a research study, factors that might distort the true association and/or influence its interpretation need to be carefully considered. This means evaluating the role of bias and considering the study’s statistical precision. In the previous issue, we discussed aspects of statistical testing and precision to explore the question of whether an effect is real or due to chance. We also considered some caveats to concluding that a “statistically significant” result is clinically meaningful.