Review Types

The preliminary search is a non-systematic research meant to help you familiarize yourself with the scope of available literature, identify key terms and appropriate synonyms, and locate prospective grey literature.

Identify relevant and related terms

During this phase, researchers should begin recording relevant and related search terms/concepts that they may incorporate into their final strategy. These terms and concepts will help ensure that your search retrieves as many relevant results as possible:

• Think about how others may describe the same concept
• What terminology is used internationally? Are there spelling differences in US English and UK English words?
• Are there any colloquial terms or phases that are used?
• Check the search terms used in other papers or systematic reviews -- you may find suggestions that you had not previously considered

Identify keywords and subject headings 

Controlled vocabularies (such as the MESH subject headings used in Medline/PubMed) provide an organized approach to the way knowledge is described. Using the same terminology throughout a database creates consistency and precision and helps you to find relevant information no matter what terminology the author may have used within their publication. Check out this tutorial from the National Library of Medicine to learn more about MeSH.  Click here to learn more about MeSH and how to find MeSH terms in PubMed. 

Utilize appropriate searching techniques 

During the preliminary search, you should familiarize yourself with the searching techniques that you'll be incorporating into your search. These include:

•  Boolean operators -- AND, OR, and NOT
• Truncation and wildcard -- retrieves all possible variations of a search term.
  • Truncating a word at the end ensures that all variation, beginning with the same root, will be retrieved. This can also be helpful for capturing both singular and plural spellings of your terms. 
  • Wildcard or truncating a word internally ensure that any variation of spelling will be included in your search results.
• Search filters -- try to use filters or limits sparingly. You do not want to restrict yourself in the following areas: time period; language; publication type; and location. 

Click here to review these and other searching techniques.

After running your preliminary searches, you should have a clear sense of what relevant literature is available along with what search terms you should include in your final search strategy. When you are ready to start systematically searching for literature, it is important to take each step in the process slowly:

• Record all utilized search terms 
• Run search in the first database
• Modify the search strategy for other database(s) --see the box Translating Searches
• Compile results from all utilized database and remove duplicates to prepare for screening
• Screen studies to include or exclude as they adhere to your inclusion criteria
• As relevant literature begins to emerge from the screening process, check the references and whether any relevant sources have been cited
• Determine relevant grey literature sources and conduct additional searching
• Hand search additional non-indexed journals or conference proceedings, if appropriate
• Update the search if significant time has elapsed since the initial search

If your final search strategy is not yielding appropriate or suitable results, there is always a possibility that it needs revision. This is a common part of the systematic review process.  See the next tab for more information. 

Returning to the drawing board to revise a search strategy is a common part of the systematic review process. Two of the most commons reasons that a search strategy may need to be revised is 1). it is producing Too Few Results or  2). it is producing Too Many Results. Additionally, your research question or needs may have changed as your research project has evolved.

Too few results?

If you are getting very few results, or none at all, you should try making your search broader. 

• Try a new database -- some databases are better equipped for subject specific searches over others. For example, if your research topic is related to sports medicine, the database SPORTSDiscus with Full Text should be considered since it covers that subject in greater depth 
• Broaden out your topic -- did you start from too narrow or specific of a place? Try using broader search terms to help widen out the scope of your topic
• Use fewer search terms --  too many search terms can often over complicate a search strategy. Think about your original research question and identify the core components that are essential to your strategy. Sometimes going back to basics will open up a new avenue you didn't consider
• Use fewer filters -- depending on your topic, there may not be that many results to begin with so filters will only further limit your options
• Use OR with synonyms
• Use wild card or truncation to include additional variations of your search terms -- see section 2. Searching Strategies for more information
• Double check your Boolean Operators -- be sure that you have properly structured your search with ANDs, ORs, and NOTs
• The topic is very new -- although it can be exciting to conduct research on a contemporary topic, there is a notable obstacle to this endeavor. If the topic is very new, then there may be limited literature available
• Analogous experiences -- try thinking about the aspects of your research that are generalizable to other things. There may be literature on something comparable or similar enough to your topic that you can use instead to support your research. For example, if you are researching HPV vaccination schedules, it may be beneficial to look at additional literature on other vaccinations that follow a similar immunization process

It is important to note that there are occasions when there simply isn't much available literature on a given topic. If this occurs, do not hesitate to reach out to the Netter librarians for assistance. They can offer guidance on how to readdress your topic and search strategy. 

Too many results?

If you have a large number of results but not many of them look relevant, you may need to make your search more specific.

• Narrow down your topic -- your topic may be too broad. Try thinking of a more focused aspect  of the topic to help concentrate your search
• Modify your search terms -- perhaps your search terms are too broad. Try and think of terms that are a bit more specific to your question
• Include additional search terms -- depending on your search terms, you may need to add more terms to help further refine your search. Try adding another concept to your search with  the Boolean Operator AND 
• Reduce the number of synonyms -- take a look at the synonyms you're using in your search. Do any of these terms have alternate meanings that are bringing back irrelevant results?
• Double check your Boolean Operators -- be sure that you have properly structured your search with ANDs, ORs, and NOTs
• Use filters -- filters such as Publication Type, Language, or Date my give you more targeted results

If you do have to revise your search strategy, you will likely have to restart the screening process. Although this may be a bit frustrating, keep in mind that searching is an iterative process that often takes multiple attempts before reaching a final search strategy.

Adapted from:  UConn Library's Find Information -- Revising & Refining your Search | Washington University in St. Louis University Libraries' Creating & Revising your Search Strategy

When am I done?

Although there is no defined "stopping" point, keep the following in mind:

• Are you finding any new ideas/information?
• Are you encountering the same authors and/or articles?
• Do you feel that you have a strong understanding of your topic?

Do note, if this is a long-term research project, be prepared to re-run your searches once every three or four weeks. You want to be sure that you are on top of the latest research.