Guide to Information Retrieval LAB

Truncation, also called stemming, is a technique that broadens your search to include various word endings and spellings. Term truncation is particularly useful for languages with case endings, as it allows you to include all the inflected forms of the search term in the search. In LAB Primo the truncation symbol is the asterisk *.

• Example: using the search term librar* will include library, libraries, librarian in the search results. 

Wildcards substitute a symbol for one letter of a word. In LAB Primo the wildcard symbol is ? which is is used to replace one letter. Using wildcards is especially useful if a word is spelled in different ways, but still has the same meanings. 

•  Example: using the search term organi?ational will include both organizational and organisational in the search results.

If you want to search for an exact phrase (search terms appearing next to each other) use quotation marks around the words, for example "wireless network".  If you don't use quotation marks around the words, many databases will look for the search words individually, so that the search results will include material where the search terms can be apart which may make the result irrelevant. The quotation marks also work in Google and Google Scholar searches. 

Boolean logic allows you to connect your search words together to either narrow or broaden your set of results. When you need more than one word to describe your search problem, you can combine multiple search terms with Boolean operators. Thoperators are AND, OR and NOT. Note that Boolean operators must be written in capitals.

AND

• Use AND to combine your search words and narrow your search results
• all search terms must be present in the search results when you use AND
• For example if you want material that discusses both cats and dogs you would use the search cat AND dog. The red area in the middle of the Venn diagram below represents the result set for this search. It is a small set because the results have to include both search words.

• Remember that you can also combine phrase searches with Boolean operators, e.g. "" AND
• Also be aware that in many, but not all, databases and search engines the AND is implied. 

OR

• Use OR to broaden your search results
• OR is commonly used to connect two or more similar concepts
• For example if you want material that discusses cats, dogs or both animals, you would use the search cat OR dog. All of the red area represents the result set for this search. It is a large set because any of the search words are valid using the OR operator.

NOT

• Use NOT in a search to exclude search terms and narrow your search.
• For example if you only want to read about cats and nothing about dogs you would use the search cat NOT dog. The red area in the Venn diagram below represents the result set for this search. It is a small set using because NOT excludes all material with dogs from the result. 

• Be careful when using the NOT operator as it might limit the results too much and leave out some valid results.

Most databases include a guide on how to retrieve information from the database. The search functions in different databases are often very similar, but they might use different wild cards or truncations. It's useful to check the guides before starting your search.