Sometimes, there are too many, too few, or too unrelated results that come from our searches. Boolean operators are keyword connectors that can assist with this. They include AND, OR, and NOT, and are also used in other disciplines, like computer science. Click on each of the operators below to learn more about how they can help you find the best possible results.
Using AND between searches will help us narrow, or decrease, our results. Use AND between terms when you want only the results that include each of your terms, especially if they're broad. For instance, searching for "dogs" will probably only bring up cute pictures; searching for dogs AND training will bring you results for the advice you're searching for.
If you add other operators like OR or NOT, make sure you close off each of the groups with (parentheses) to keep everything organized. Note that all operators should be in CAPS, because your search bar is not smart enough to recognize it in lower case.
The search pictured below: Peanut butter AND jelly
Other examples: titanium AND dental AND biomedical engineering
Using OR between terms will broaden, or increase, your search results. Use OR in between related terms and synonyms to maximize the number of related results. On our Venn diagram below, we can see that the entire chart is highlighted - because using OR between terms means anything goes!
If you add other operators like AND or NOT, make sure you close off each of the groups with (parentheses) to keep everything organized. Note that all operators should be in CAPS, because your search bar is not smart enough to recognize it in lower case.
Example search: patient lift OR patient hoist OR patient transfer device
Example search with multiple operators: (patient lift OR patient hoist) AND (human factors OR ergonomics)
Using NOT will narrow, or decrease, the number of results. NOT works by excluding the unrelated terms you list in relationship to the ones that you do want to search for. Since NOT excludes terms, it's not something that can be searched for by itself. It has to be attached to terms that you want!
For instance, (Nirvana OR Kurt Cobain) NOT Buddhism. This should give you only results about the band Nirvana, or its front man, Kurt Cobain, and exclude anything about Buddhism, which is where the term nirvana originates.
Another example search: ((Seizure detection) AND (device OR technology)) NOT "search and seizure"
This search will include results for tech that detects oncoming seizures, but not police procedures for a search and seizure. Note the sets of parentheses to separate (AND/OR) and NOT, and that "quotation marks" will search for exact phrases.
The Venn diagram below shows the results of searching peanut butter NOT jelly. Notice that the center results (PB&J) are excluded from the results. This is because any results that include jelly are thrown out with NOT. Imagine someone has a jelly allergy - having a PB&J sandwich would still make them have an allergic reaction!
Sometimes, searching for terms doesn't work well - even with AND, OR, and NOT. We can search for specific phrases (e.g., words that make sense in a group or as a set of terms) by using quotation marks (" ") around that phrase. Results that appear after using quotation marks will appear exactly as you type them, so make sure you've spelt everything correctly!
Example search: "operating deflection shape" OR ODS
If you have a term that has a hyphen (e.g., non-destructive testing), consider testing the same search with and without a hyphen. While many databases will include results for both either way you search, this isn't always the case.
Broadening your search results doesn't have to be difficult - in fact, you can do it instantly when you end a word prematurely with a *. The asterisk (the name for that little star shape, *) can be used as a "wildcard" to fill in the rest of the keyword. For instance, typing mechani* will provide results for the following words:
Search: Mechani*
Results include: Mechanic, mechanics, mechanical, mechanism, mechanisms, mechanistic, etc.
Note: Not every database uses the asterisk as a wildcard. Some use a percent sign (%) or pound/hashtag (#) or have them operate slightly differently in the search. If you're unsure, navigate to the database's search help page to ensure you're using the correct symbol.