Bias in research.

Bias is a systematic inconsistency in research that contaminates the primary comparison. There are several forms of bias, and there are specific methods of minimizing them in different study designs. The randomized controlled trial (RCT) is the gold standard to which all other study designs are compared. However, errors can be made at various stages of a RCT that introduce bias. Furthermore, not all questions can be addressed by a RCT, and in some cases another study design may be more appropriate. Observational studies are more prone to bias, but, when properly conducted with rigorous methods to minimize bias, these studies can be valuable in clinical research.