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Dental Assisting and Dental Hygiene

A research guide to find dental resources from the EFSC Libraries.

Levels of Evidence

Consider the type of research article retrieved. The higher on the evidence pyramid, the more credible the article.

Levels of Evidence Pyramid

From University of Illinois Chicago. Library of the Health Sciences. Evidence Based Medicine. https://researchguides.uic.edu/ebm. Used under a CC BY-NC license.

Levels of Evidence Definitions

The following definitions comes from the BMJ Clinical Evidence Glossary of EBM Terms.

Systematic Review: A review in which...appropriate methods have been used to identify, appraise, and summarise studies addressing a defined question. It can, but need not, involve meta-analysis. A meta-analysis is a statistical technique that summarises the results of several studies in a single weighted estimate, in which more weight is given to results of studies with more events and sometimes to studies of higher quality.

Randomized Controlled Trials: A trial in which participants are randomly assigned to two or more groups: at least one (the experimental group) receiving an intervention that is being tested and another (the comparison or control group) receiving an alternative treatment or placebo. This design allows assessment of the relative effects of interventions.

Cohort Studies: A non-experimental study design that follows a group of people (a cohort), and then looks at how events differ among people within the group.  Prospective cohort studies (which track participants forward in time) are more reliable than retrospective cohort studies (which track participants backwards in time).

Case-Control Studies: A study design that examines a group of people who have experienced an event (usually an adverse event) and a group of people who have not experienced the same event, and looks at how exposure to suspect (usually noxious) agents differed between the two groups. This type of study design is most useful for trying to ascertain the cause of rare events, such as rare cancers.

Case Series: Analysis of series of people with the disease (there is no comparison group in case series).

Source:

BMJ Publishing Group. (2012, September 20). A glossary of EBM terms. In EBM Toolbox. Retrieved from https://bestpractice.bmj.com/info/toolkit/ebm-toolbox/a-glossary-of-ebm-terms/