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Evidence searching and critical appraisal

Constructing an effective search

Primary research can be found in the databases that Knowledge and Library Services subscribe to, each covering different areas of research.

These databases do not respond well to naturalistic searches so we have to create a structured search to get the best results.

  1. First, break down your topic into its separate concepts. In our example that would be "parenteral nutrition" + "cystic fibrosis". If appropriate, you can use the PICO framework (Population/Patient, Intervention, Comparison, Outcome) to identify the separate concepts in your search topic.
  2. For each concept in your search topic, identify all the relevant keywords you'll want to use, including exact or rough synonyms (e.g. search for the phrase "parenteral feeding" as well as "parenteral nutrition"). Consider acronyms or abbreviations you might want to include (e.g. "CF" for "cystic fibrosis"), alternative spelling (e.g. leukemia vs leukaemia), plurals (child, children). Databases won't automatically include synonyms and alternative terminology so you need to specify these.
  3. Decide on the limits of your search results (date published, type of evidence, language etc)

Make a note of all these decisions so you can run the same (or similar) search in mutliiple databases.

Building a structured search

You can now build a structured search that will work well in databases that contain primary research. We do this using Boolean operators. These operators tell the database how to combine your search terms. 

AND

AND tells the database to only bring back results that include all your search terms. Use it to combine the search terms for each concept in your search e.g "parenteral nutrition" AND "cystic fibrosis". Use quotation marks (" ") around phrases to ensure the databases searches for your terms as phrases rather than individual words.

OR

OR tells the database to bring back results that include both search terms. You use it search for the synonyms etc. that you identified for main search terms  e.g. "cystic fibrosis" OR CF

NOT

Use NOT to exclude search terms e.g. Kittens NOT cats. Use this with care to make sure you don't exclude useful results.

Combine all together

You can create complex searches by combining Boolean operators together e.g. ("parenteral nutrition" OR "parenteral feeding") AND ("cystic fibrosis" OR CF). 

Watch the video below to see this in action, including a demonstration of other advanced searching techniques you can use.