An Introduction to Common Systematic Errors in Medical Research

Considering the continuous increase in number of published articles by Iranian researchers in recent years, the matter of quality in design, implementation, analysis and publication of articles is receiving its relevant attention. Of issues in quality of articles and studies are methodological errors. There are different kinds of errors that a researcher may fall into during various phases of a study. Of these errors systematic ones (or biases) can be counted. In this paper we aim to shortly introduce various sorts of biases that might happen in medical research. These biases are of two categories; selection and information biases.