In many search engines, you can use three special search words to make your searches specific and your results relevant.
These are called Boolean operators (because they were first used in formal logic by George Boole).
Take a resource that contains some journal articles that contain the word chocolate, some articles that contain the word health, and some articles that contain both words (and many articles that do not contain either word, but won't show up in our search results).
You can combine your search terms using Boolean operators to find only specific sets of articles.
This will find all articles that have both the word health AND the word chocolate in the same article.
All the articles in the results must mention both topics.
This will find all the articles that have the word health OR the word chocolate, or both, in the same article.
This is good for finding articles where authors have used different words or phrases to describe the concept in which you are interested, such as cocoa OR chocolate.
This will find all articles that have the word health but do not have the word chocolate.
This is good for excluding articles that include specific topics you do not want to find. e.g. fruit NOT apple will search for articles that use the word fruit, but If the article has the word apple, it will not be included in the results even if the article has the word fruit.
This Boolean operator is not used as much as AND or OR, because often you are seeking to find articles, not exclude them.
Your search describes the words you want to find in each and every article.
Sometime you will have a single-line search box and you have to type in AND or OR.
Sometimes you will have multiple search boxes and you choose AND or OR from a drop-down selection.
Many search engines hide a multi-line search under an Advanced link (do you agree it should be called advanced?).
Some databases will accept these Boolean operators in upper or lower case or mixed case: and AND anD And aNd
However, some databases will only accept them in upper case.
If you use lower case, these databases will search for the word and or will simply discard the word from the search.
Upper case always works, so please get into the habit of using them in upper case.
Watch the video below for an example of searching using Boolean operators
Click the Transcript button to see the transcript of the video above
This is George Boole, a British mathematician and one of the fathers of computer science.
Since we use computers to search for sources, it's helpful to utilise his Boolean operators, AND, OR, and NOT.
Let's explore how these operators can refine our searches into "A struggle for the ages: Coca-Cola versus Pepsi".
I could search a library database for Coca-Cola.
In this case, I got back eight thousand, six hundred and forty (8,640) results.
So any article that included the keyword "Coca-Cola" was returned in my search.
I could also search the database for Pepsi - now I get back four thousand and sixty (4,060) results.
So I only retrieve articles that included the keyword Pepsi.
If I search for both keywords, connecting them with the AND operator, I only return eight hundred and forty-six (846) results.
Where did all the other results go?
By connecting with AND I limited my hits to only the articles that included both keywords.
So any article with just one keyword was eliminated from my result list.
Conversely, if I connect both keywords with the OR operator, I return eleven thousand, eight hundred and fifty-four (11,854) results.
This is much more than my previous searches.
By connecting with OR, I expanded my hits to any article that included either keyword.
Some may just cover Coca-Cola, some may just cover Pepsi, and some may cover both.
Finally, I could connect both keywords with the NOT operator, and I return seven thousand, seven hundred and ninety-four (7,794) results.
This is eight hundred and forty-six fewer results then I got searching for Coca-Cola alone.
What's going on with those eight hundred and forty-six (846) articles?
They must also include the keyword Pepsi.
By using the NOT operator I removed the subset of Coca-Cola articles that also talked about Pepsi.
So help yourself find relevant results quickly, by remembering good old George, and connecting your keywords with the appropriate Boolean operators, AND, OR or NOT.
Reminder: To get the mutli-line search interface in some databases, select Advanced search ("advanced" doesn't mean more complicated, sometimes I think it should be called "specific search" rather than "advanced search").
In the Google Scholar search below:
Look at the results - when you use OR you get:
Both Google and Google Scholar use a different syntax for NOT then most Library databases they use a minus sign or dash at the front of the word.
Instead of "mobile phones" NOT security, type in "mobile phones" -security
Compare that to the number of results when searching just for "mobile phones".
ERIC is a "database" for finding education-related journal articles and other material
Click the button below to connect to ERIC and try these:
Almost all databases use NOT instead of the dash/minus sign used by Google
You want to find all the articles that use the phrase "university transition", AND all the articles that use the phrase "college transition".
Which search would you use?
Unlike the question, you don't search for the entire set of results, your search describes EACH article.
In this case you don't particularly want each article to have both phrases (although that would be OK). In each article, you want to find the phrase "university transition" OR the phrase "college transition"