How to avoid bias: methodological vigilance

One of the main purposes of choosing and developing a strategy for clinical research is to attempt to reduce bias. The avoidance of bias is build on methodological vigilance: The researcher should be familiar with the most common sources of bias. This vigilance is supported by guidelines and the development of methodological standards. Where sources of bias cannot be eliminated it is important to identify them so that they may 'be considered when conclusions are drawn from a study. Randomized controlled trials (RCT) have the greatest potential to reduce bias, but conducted without methodological vigilance the trial's guarantee of lack of bias is lost. Methodological vigilance has also to be applied when results of different RCT's are combined and used for clinical or research purposes.