Bias can be introduced at any part of the research process—including study design, research implementation or execution, data analysis, or even publication (Hsu et al., 2008; Pannucci & Wilkins. 2010). Any time you undertake research, there is a risk that bias, or a systematic error, will impact the study’s results and lead to conclusions that tell an incomplete or inaccurate story (Popovic & Huecker, 2023).
Critical appraisal of a d study is also a process of identifying potential bias of the study.
Here are some common types of biases in research. For other types of biases and details such as background, examples of biases, impact and preventive steps, please check Oxford University Centre for Evidence-Based Medicine (CEBM)'s Catalog of Bias.
| Common Bias Types | Descriptions |
| Selection Bias | Participants in research may differ systematically from the population of interest. It occurs when the individuals examined differ from the group of people the investigators aim to study. |
| Allocation/Assignment Bias | Systematic difference in how participants are assigned to comparison groups in a clinical trial. |
| Performance Bias | Systematic differences in the care provided to members of different study groups other than the intervention under investigation |
| Detection Bias | Systematic differences between groups in how outcomes are determined |
| Attrition bias | Unequal loss of participants from study groups in a trial |
| Reporting biases |
A systematic distortion that arises from the selective disclosure or withholding of information by parties involved in the design, conduct, analysis, or dissemination of a study or research findings Researchers have previously described seven types of reporting biases, including publication bias, time-lag bias, multiple (duplicate) publication bias, location bias, citation bias, language bias and outcome reporting bias (Higgins & Green, 2011). |
References
Biases Archive. (n.d.). Catalog of Bias. Retrieved July 24, 2023, from https://catalogofbias.org/biases/
Higgins & Green. Definitions of some types of reporting biases. Cochrane Handbook for Systematic Reviews of Interventions, v5.1.0. 2011.
Popovic, A., & Huecker, M. R. (2023). Study Bias. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK574513/
