The following steps outline a general search strategy for databases.
1. Identify key concepts
For clinical questions, PICO framework can help you to identify the main concepts. For general research questions or when PICO doesn't apply, find the nouns in your research question, then pick the key concepts. As most often, concepts are nouns. In addition, thinking about what key concepts the articles should include in the search results.
2. Collect search terms
When collecting search terms, include keywords/free text that authors might use to describe the same concept, and controlled vocabularies in the search. Use Boolean OR to combine the terms.
With keywords, you can search using natural language, but you also want to be thorough and try using several variations of the concept you are searching for. Common keyword variations to consider:
Synonyms - toddler, preschooler, child
Singular and plural versions of terms - child, children
Controlled vocabularies are standardized and organized arrangements of words and phrases and provide a consistent way to describe data. Metadata creators assign terms from vocabularies to improve information retrieval. Medical Subject Heading, or MeSH, is the NLM controlled vocabulary thesaurus used for indexing articles in PubMed, MEDLINE, Cochrane Reviews and part of their clinical trials, and CINAHL (CINAHL has its own subject headings, but accepts MeSH as the standard vocabulary for disease, drug, anatomical, and physiological concepts). Not every database has controlled vocabulary, like Scopus, it doesn't use any controlled vocabulary.
Why Include Controlled Vocabularies in the search?
MeSH group terms into concepts, or in other words, multiple alternative words for the same concept can be retrieved by using the MeSH term. See examples below:
If you search MeSH term "otitis media", in the search result, you should be able to see articles that use any of the following terms: middle ear inflammation, middle ear infection, otitis media if the article was indexed by the MeSH term "otitis media".
If you search MeSH term "Neoplasms", in the search result, you will see any of the following terms: tutor, tumors, cancer, cancers, neoplasm, etc.
3. Search each concept separately.
Sometimes you need to adjust the search, like use less concepts when you have fewer results. If you search each concept separately, it will be easier to combine as less or as many concepts as you wish.
4. Combine concepts.
Use Boolean AND to combine difference concepts.
5. Apply filters.
Use age, gender or study types filters as needed. In PubMed, you will see filters like systematic review, RCTs, observational studies, etc under the ARTICLE TYPE filer.
Keywords, also known as search terms are the words that you enter into database search boxes. They represent the main concepts of your research project.
Keywords summarized:
When searching in databases, keywords can be used to...
Searching is an iterative process that will take trial and error. Be patient -- you'll find the right words to use.
Boolean operators are words (AND, OR, and NOT) that are used as conjunctions to include or exclude keywords in a search. Their use leads to more focused and precise results. These operators help string your search terms together. combining them effectively. Most databases utilize boolean operators for searching.
AND
Phrase searching includes placing quotation marks ("__") around two or more words to create a search term. This searching technique dictates to the database to retrieve only those results in which the exact phrase appears.
A search for attention deficit disorder = attention AND deficit AND disorder -- without phrase searching
A search for "attention deficit disorder" = "attention deficit disorder" -- with phrase searching
Note: Phrase searching in individual databases may vary. Check the help pages in each database for additional information.
Consider using synonyms and abbreviations to enhance your searching. The English language is filled with many different ways of saying the same thing. Using synonyms and abbreviations while searching in databases will help ensure that you are able to create a comprehensive search string that will capture all relevant articles.
Synonyms are words that have the same or similar meaning to another word or phrase. Many concepts have different terms that can be used to describe them. For example, some additional keywords that can be used for Pediatric Obesity include:
If you are not sure how to find synonyms for your terms, try looking in PubMed's MeSH (medical subject headings) database. Most entries in the MeSH database include a list of 'Entry Terms'. These are all the terms that you could search that would be still ultimately connect to a specific MeSH term in PubMed.
When searching, you should always spell out any abbreviations that might be included among your search terms. For example, if yoy are searching for articles on PTSD, you should spell out the phrase, post-traumatic stress disorder, as well as include the abbreviation.
Truncation, also called stemming, is a technique that broadens your search to include various word endings and spellings.
Child* = child, child's, childhood, children, children's,
Some important things to note about truncation:
If I searched toxic* in PubMed, my search results would include....
Wildcards are another searching technique. They are used in search terms to represent one or more other characters.
