Online Research: What do you want to know? Part 2: Keywords and Boolean Operators

The blinking cursor of the search bar may be as intimidating as deciding what topic to research. Typing a general search term, such as literacy, will return thousands upon thousands of results which must be narrowed down. How does one go about sifting through all those results?

In this case, the topic can be further clarified by thinking what about literacy the search is trying to determine — say the paper the writer is working on discusses whether literacy education helps people overcome issues of poverty. From this question the writer can use:

 Keywords: literacy, education, poverty

Or phrasing: literacy education overcoming issues of poverty

For either, Boolean operators (which are words algebraic logic operators) can be used to create sets of search results by joining or modifying keywords. Three common Boolean operators familiar to most students are “AND,” “OR,” “NOT.”

The usage of the term AND seems pretty obvious (i.e. this AND that). But its effective use is not quite as simple. If searching for this and that, one merely needs to type – this that – and a search engine will factor in the missing AND in the space between the two words. However, if the search is more complicated (i.e. literacy education overcoming issues of poverty in Chicago housing projects) the term AND can help design sets that might bring back better results.

For example: literacy education AND poverty AND Chicago housing projects

However, this query will still not be quite accurate enough. In fact, unless the person implementing the search uses “quotation marks” to group the words together in the phrased query, the search will return every result that contains at least one of the words in the phrase. In order to narrow the search even further it becomes necessary to group these words together.

For example: “literacy education” AND “poverty” AND “Chicago housing projects”

The search should now only show results that contain these words somewhere in the returned documents.

A quick breakdown of other Boolean operators:

OR: This operator affords for at least one term or phrase to be present in the search, e.g. “literacy education” or “reading education”

NOT: This operator tells the search engine to exclude a term in a search. Also, NOT is often used in conjunction with another operator such as AND, e.g. “Literacy education” AND “poverty” NOT “housing projects”

NEAR: This operator asks the search to find a term near another term (at least within 16 words of the other keyword), e.g. “Literacy education” NEAR “poverty” or if the goal is to find literacy education in Chicago — “Literacy education” NEAR Chicago.

( ) or Nesting: Parentheses are used to clarify conditions in complex searches. The operation requires a keyword or a group of keywords to be searched first before the entire search is completed. For example (“literacy education” NEAR “poverty”) AND (“Cabrini Green” OR “Housing projects”)

*: Asterisk signifies a string; for example if a word has multiple suffixes or the searcher only knows partial spelling of the entire then an asterisk can be used to pull up terms that contain part of that word, e.g. “project*” for projects or project.

-: Minus symbol indicates a similar operator to NOT. For example, the search “Literacy education” AND “poverty” -Chicago would result in searching for literacy education and poverty but exclude any documents that contain the word Chicago.

N.B. Special thanks to Joe Barker of the Teaching Library at The University of California, Berkley. He has created comprehensive PDF explaining Boolean terms with visual aids which readers can find here.

Bernard M. Cox