Basic Operators Strategy

Tutorial Directory

Basic (Boolean) operators

Operators are usually symbols (like +, - or " " ) or words (AND, OR, NOT) that change the way search engines interpret query terms.

AND

Requires all terms to appear somewhere in the document, in any order. Examples: curriculum AND high AND school. The space bar substitutes for AND/+ in most search engines: curriculum high school

AND is a good general search strategy; search engines like Google will return as many of the keywords as possible. Other search engines may not return any results unless all the keywords are contained in a result.


""

Requires all terms within the quotation marks to appear exactly as written. Creates a highly specific phrase. Example: "high school curriculum"

Quotes is useful when you have an exact phrase to locate or want to combine keywords to reduce the number of different elements in a query.


NOT

Excludes documents containing whatever follows it.
Example: NOT high school curriculum. Using minus also works: -high school curriculum (so space after the minus sign)

NOT removes unwanted keywords from the results; however, it could eliminate relevant results that contain those keywords.


OR

Includes any page with at least one of the terms. Example: high OR school OR curriculum

OR expands the search--which may be necessary if few results are obtained to start with.


Why use operators?

It's entirely possible to locate good information without operators--other than default AND (spacebar). Therefore, the best strategy is to start by searching for 2-5 keywords by placing spaces between them. If this produces too many or too few results, use the fundamental AND strategy:

    increase the results by using fewer keywords
    decrease the number of results by using more keywords.

If there is an exact phrase that is known, putting quotes around the phrase will decrease the results. Otherwise, it may be counterproductive to use quotes. The drawback to this operator becomes apparent when relevant results are eliminated because they don't contain an exact match (e.g., a result matches all but one of the terms). Use quotes only when you are confident in the phrase to be retrieved.

Use NOT only when an unwanted keyword shows up in the results. The unwanted term may crowd out more relevant results which don't appear on the first page of results. This is not a common operator to use. When in doubt, avoid it.

Finally, OR inflates results so much that is becomes hard to find relevant results. It's an ineffective strategy to search for terms that should beong together by placing an OR between them. The results tend to be disconnected and unfocused.

Be aware of invisible operators

As mentioned, a search engine may insert an invisible AND whenever the spacebar is used. Older search engines (e.g., Alto Vista) once inserted OR in place of AND, which is Google's present practice). How can you tell? Look at the results. If the top results contain only one of the keywords from the query, there's a good possibility, the default search uses an invisible OR.

Why the difference? Search engine algorithms are designed with operators that developers believe will be most helpful to users. You can always override the invisible default operator by using a visible operator in place of a space.

Where do operators go in a query?

The + and the - operators must be placed in front of and immediately next to (without any space) each query term you want to it to apply to. Like this: +Miami +dolphins -football.

The "quotes" operator must surround the terms you want to include in a phrase like this, "Buffalo Bill". However, most search engines are tolerant of spaces between the quotes and the terms.

AND, OR and NOT can be used with spaces surrounding them, in which case the space doesn't change the desired function. The operator affects only the word that follows. For example: Miami Dolphins NOT football returns hits containing the the first two terms but not the last.

Use operators to keep queries compact

One of the advantages of operators is to keep queries from getting too long. The query causes poverty United States today contains distinct 5 keywords. It could be shortened to 4 by using quotes: causes poverty "United States" today This would allow an additional keyword to be included that improves the query and still is a reasonable length: causes poverty "United States" 2015 OR 2016.

ALWAYS Read the Snippets

Using operators involves an IN and OUT strategy that is part of speculative searching. Therefore, you can never quite be sure what the results coming OUT will be. The only way to determine the effect of operators is to read the snippets--skim the results. Look for the keywords you entered. Are they all there as expected? Are other terms getting in the way? If so, try a NOT query. Are there too few results? If so, use an OR query and/or reduce the number of keywords in the query. Unless you look at the results, you'll never know if your use of operators is effective.

Advanced operators

Advanced operators include those that enable you to limit your search to a particular Internet domain, to a particular location in a Web page, to pages within a site, or to a particular document format.  For more information on advanced operators, see the Advanced Operators Micro-Module.

Authored by Lora K. Kaisler (2003), updated by Carl Heine (2016)