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Evidence-Based Practice (EBP)

In addition to the basics of EBP and PICO, this guide answers questions about primary vs. secondary sources, where to look for evidence, and how to search to get the best results.

Hierarchy of Evidence

Hierarchy of Evidence pyramid showing lower quality, higher bias evidence at the base and higher quality, lower bias evidence at the top. The lowest quality evidence is ideas, editorials, and opinions. Primary sources in the middle of the pyramid, arranged from lowest to highest, include case series, case reports, cross-sectional studies, case-control studies, cohort studies, and randomized controlled trials. Secondary sources at the top of the pyramid, arranged from lowest to highest, include systematic reviews, meta-analyses, and practice guidelines.

Not Finding Enough Evidence?

Sometimes, despite your best efforts, you find few or no articles related to your clinical question. Not every PICO(T) question has a perfect article, so you may need to make a decision as to what matters most to your research. If you are unable to find evidence, here are some strategies:

  • If you have flexibility in choosing a topic for your paper, do some preliminary research to see what you can find, and design your PICO(T) around the available evidence. In other words, find an alternative assessment, treatment, or service delivery option that is evidence-based.
  • Reconsider your search terms. Try making your search broader by adding more synonyms or common acronyms to your search terms.
  • Consider research from similar or related populations, interventions, or outcomes. Use your clinical judgment to decide if such information could be helpful for your paper.