An Introduction to Common Systematic Errors in Medical Research


Amir Almasi-Hashiani 1 , Jafar Hassanzadeh 2 , Babak Eshrati 1 , * , Esmaeil Khedmati 3

1 Department of Epidemiology and Biostatistics, Arak University of Medical Sciences, Arak, Iran

2 Department of Epidemiology, Faculty of Health and Nutrition, Shiraz University of Medical Sciences, Shiraz, Iran

3 Department of Public Health, Qom University of Medical Sciences, Qom, Iran

How to Cite: Almasi-Hashiani A, Hassanzadeh J, Eshrati B, Khedmati E. An Introduction to Common Systematic Errors in Medical Research, Zahedan J Res Med Sci. 2012 ; 14(10):e93168.


Zahedan Journal of Research in Medical Sciences: 14 (10); e93168
Published Online: March 07, 2012
Article Type: Review Article
Received: November 16, 2011
Accepted: January 26, 2012


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.


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