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Public Health

Guide to library research for evidence-informed public health practice.

Want more help?

All databases should have a Help page that is usually located in the top right-hand corner. There you will be able to find more information about the contents presented on this library page as well as additional search functionalities.

Want even more help? 

Request a research consultation with a librarian.


When searching for research evidence, consider that there is a hierarchy of evidence. The NCCMT Evidence-Informed Public Health website presents a pyramid of research evidence with different levels of evidence and provides the following guidance: 

"Your search strategy should aim to locate the strongest quality and most relevant evidence first. When searching for quantitative evidence (e.g., effectiveness of an intervention, health effects, cost effectiveness, etc.) some study designs are considered stronger than others. It is important that the research design is the most appropriate to answer the question being asked."

Higher levels of evidence consist of syntheses of studies (e.g. systematic reviews) and summaries (practice guidelines). Bibliographic databases like Global Health, Ovid MEDLINE etc. will often include evidence syntheses and guidelines (in addition to individual studies), which can be easily retrieved by limiting your search results by publication type or study design. Databases that prioritize high-level evidence are sometimes referred to as evidence-based practice databases, some of which are available through the library (e.g. Cochrane Library) and others are freely available to search (e.g. Health Evidence). 

Research databases often give you the choice of performing a basic or advanced search (note that most library databases accessed via Queen's University Library will default you to the advanced search).

A basic search can be incredibly helpful when looking for a few good articles on a topic or when you're doing some preliminary searching/work. However, a basic search is not recommended if your intention is to perform a comprehensive search. Furthermore, many search topics are complex and it can be to your benefit to use advanced search functionalities. When completing assignments with a literature search component, many instructors want to see evidence of an advanced search that demonstrates a deeper understanding of how databases work and function.

The following page works through search options available on Ovid. Ovid is a search interface/platform that is available for a number of different databases such as Global Health, MEDLINE, Embase, PsycINFO, etc. The examples and screenshots provided are from Ovid MEDLINE and may function or appear slightly different on other Ovid databases. Similar principles apply to other search platforms such as Ebsco for searching the CINAHL database. 

Basic Searching

The basic search in many databases operates similar to conducting a Google-type search:
  • Search terms are generally ‘AND’-ed automatically
  • The search algorithm usually attempts to include related terms (ex. searching "childhood" may retrieve "children")
  • Results are often sorted/displayed by relevancy rather than publication year
  • Generally a quick and easy way to locate some relevant records on a topic

Basic search in Ovid databases:

  • Basic search retrieves records where your search terms (and related terms) appear in the record title, abstract, author keywords, database-specific subject headings etc.
  • The basic search mode does not allow you to combine search terms with OR. If you use OR in basic search, Ovid will just ignore the command. If the basic search is not including the necessary synonyms and related terms you want in the search, you can run different iterations of the search by substituting different synonyms and related terms (read more below)

Including related terms in Ovid databases:

  • Like a Google search, many databases will try to include related terms for your search terms. These database algorithms work at a very basic level. For example, the Ovid search above will search for children as a related term for childhood, but not adolescents. You can review what related terms the database includes to the left of the search results to understand how your search was interpreted (see below)
  • In the search information below you can also see that obese was included as a related term for obesity
  • The displayed results will highlight your exact search terms in yellow, and related terms in purple
  • If the database does not include the related terms you are interested in, you can run different iterations of the search by substituting different synonyms and related terms. For example, after searching for: physical activity adolescent obesity, you may want to try: exercise childhood obesity


Database Limits

Most databases will allow you to narrow your search results by applying limits. The options will vary by database but often include limits for publication date, publication types, age groups and language. 

Limits in Ovid databases:

  • You can view limits underneath the main search box
  • If you would like to see even more limit options, you can select "Additional Limits" below