Control of risk of bias: cornerstone for health research internal validity

Abstract

Health research results must approach the truth. In quantitative designs this is known as internal validity, which depends on control of risk of bias. Bias are “errors in study design that leads to an incorrect estimation or non-valid for the effect or parameter being studied”.
They can occur at the moment of participants inclusion or selection bias, or when collecting the information or information bias.
These bias once introduced in the study cannot be repaired. The importance to know about and control risk of bias lies in the fact that it permits the development of research with internal validity, pending to explain other necessary important components of research designs such as confounders and precision.