What does the term 'bias' encompass in clinical trial evaluations?

The term 'bias' in clinical trial evaluations refers to systematic deviations from the true treatment effect estimates. This means that bias occurs when the results of a study consistently lean in a particular direction due to factors that affect the study design, execution, or data analysis processes, which can distort the findings and lead to incorrect conclusions about the effectiveness or safety of a treatment.

Bias can arise in various ways, such as selection bias, where certain types of participants are more likely to be included in the trial than others, or measurement bias, where outcomes are assessed inconsistently or inaccurately.

The systematic nature of bias is what distinguishes it from random errors or variability. While random errors or variability can occur in any study, they do not systematically skew the results in a particular direction. Thus, understanding bias is crucial for ensuring the integrity of clinical trial results and making informed decisions based on the findings.