Once you have developed a list of keywords, you will need to start thinking about how to use them effectively in your search. If you regularly use search engines like Google, you may be accustomed to typing a question or sentence directly in the search box. While that may work, it will also inevitably find many erroneous, irrelevant, or unacceptable results. In other search tools, like the library catalog or databases, this type of searching will not work.
Instead, using what is called a search statement will help you best approach your research. You will use your keywords, in combination with exact phrase searching, specialized search words called Boolean terms, and modifiers known as wildcards, to develop this statement. Boolean terms (AND, OR, NOT) are used to either narrow or broaden your pool of results when used with multiple keywords. Boolean terms usually appear in all uppercase letters to distinguish them from the keywords. Some search tools require capitalized Boolean terms as well.
Enclose phrases, proper names, and titles with quotation marks. Adding quotations keeps all the words together so your search engine, database, or library catalog does not search for them as individual words.
Example:
physical activity → "physical activity"
Affordable Care Act → "Affordable Care Act"
Ernest Hemingway → "Ernest Hemingway"
Use AND to connect keywords and narrow results.
Finds results where both keywords are present in the search fields.
You will not want to use every term you have identified. Remember, every time you add a word you will narrow your search and receive fewer results.
Examples:
→ "weight lifting" AND obesity
→ exercise AND health AND elderly
→ "physical activity" AND diabetes AND "aging adults"
Use OR to search with synonyms and expand results.
Finds results where either keyword is present in the search fields.
This is an ideal to search strategy to use with synonyms. This can be particularly effective when combined with an AND term.
Examples:
→ "physical activity" OR exercise
→ elderly OR "aging adults" OR "older adults"
→ (running OR cardio) AND obesity
Use NOT to eliminate keywords from results.
Eliminates results that have a keyword present in the search fields.
This is helpful to eliminate topics that would likely appear in your search results, but that aren't relevant to your specific research topic.
Examples:
→ exercise NOT "weight lifting"
→ obesity AND walking NOT running
→ exercise OR "physical activity" NOT teenagers
When selecting keywords, the database will look for that word, but not necessarily all variants of the word. Plurals, abbreviations, and spelling variants can all cause your search to miss relevant information. This is where wildcards and truncation symbols come in. While they can vary from database to database, common wildcards include:
You can use an asterisk at the end of a keyword to search for all words that start with those letters. For example, using the keyword "teenagers" would fail to retrieve "teen, teens, teenage, or teenager," but the keyword "teen*" would retrieve all of those words. Asterisks can also be used within words or between words in a search.
You can use a hashtag within a word to look for variant spellings that add a letter, which is common in British vs American spelling. For example, the keyword "anesthesia" might not find "anaesthesia," but the keyword "an#esthesia" would find both. Many databases are do automatically search for variant spellings without a wildcard, but not always.
You can use an question mark within a word to substitute for a single letter. For example, the keyword "ne?t" would retrieve "neat, nest, or next."
You have options to combine all of these methods with parentheses following the same kinds of rules as parenthesis in mathematics (i.e. what is inside the parentheses are handled together then combined with what is outside of the parentheses).
For a search on preventing drunk driving among teenagers, you could come up with a final search statement:
(teen* OR adolescen* OR "young adult*") AND ("drunk driving" OR DUI OR DWI) AND (prevent* OR mitigat* OR decrease)
IMPORTANT: Not all search statements need to be equally complex in use of synonyms, wildcards, Boolean searching, etc. What is important is having some tools in your toolbox to use strategically to get the information you need.