MW5106: A Survey of Research Methods

Use the visual provided by the Evidence Based Pyramid, below, to discover a hierarchy of evidence resources.  Remember that you may not necessarily be able to find a Meta-analysis or Systematic Review on your particular topic, depending upon the amount of research that has been completed. 

Tip:  The instructions for the finding particular study types in PubMed suggest you "AND" certain study types in your searches, but don't literally use the quotation marks in your search!  Search for: breech presentation AND randomized controlled trial, not breech presentation "AND" randomized controlled trial.

For your assignment, you’ll need to know how to find different study designs (e.g. cohort studies, systematic reviews), so here are suggestions of how to do this using PubMed.

Topic: What is the effect of maternal obesity on pregnancy outcomes?

#1 Best (i.e. “cleanest”) way to limit to study type: Using Filters/Type of Article:

• Search example: obesity AND pregnancy outcomes (these are both MeSH terms).  Perform this search, then use the Article Types Filter to limit to a study type (clinical trial, review, etc.).  You may need to click on Additional Filters in order to see all the study types.
• Note that only some study types are available in the Filters list (not cohort or case-control studies).

Here is another way to find a particular study design:

#2: See if the study type you’re looking for is a MeSH term.

• I’ve already done the work for you, and know that Cohort Studies and Case-Control Studies are MeSH terms, so search for: obesity AND pregnancy outcomes AND cohort studies
• Also, try following the guidance on the Evidence Based Pyramid  (in box #1) by adding AND cohort study, or AND case-control study, to your search.  This way PubMed will recognize both the MeSH term and the narrower terms under it.