Searching the Digital Library

Boolean operators are the most essential tool in a researcher’s toolkit. These words: AND, OR, and NOT, allow a researcher to narrow or broaden their search by instructing the database how to connect your search terms.

AND

Using AND narrows your search results. When placed between two keywords, the AND tells the database you only want to see articles that contain both keywords. For example, look at the following search:

This search will only show articles that reference the budget deficit in the United States. The AND ensures you find articles that match your topic as closely as possible. You can also add more keywords to be more specific:

When using the AND make sure to be specific enough to find relevant articles, but not too specific where you’re unable to find enough for your assignment.

OR

The OR broadens search results. While the AND looks for articles that have all of the keywords, the OR tells the database to find at least one of them. Look at the following example:

 

The OR tells the database to find articles that mention heart attacks, as well as articles that mention myocardial infarctions. This search will find articles that use either the common or medical term for the same idea.

NOT

The NOT removes articles from search results. As an example, let’s say you need research about special education in a foreign country. Run a search for special education and you’ll find that most of the articles in your search results focus on special education in the United States. However, if we conduct the following search:

This search will look for articles on special education, but will remove any that reference the United States. What is left is a series of articles focused on special education issues in countries from all over the world.

Using Boolean logic is essential to locating the best sources, but it is often a process of trial and error. If the initial search doesn’t have a lot of useful sources, don’t give up! Try different combinations of keywords and Boolean logic until you find a search that works.

Nesting

Nesting is when you surround parts of your search query with parentheses. This is done to tell the database’s search engine which part of your search to perform first. Many, though not all, databases allow this technique.

Example: (human AND rights) AND NGOs

The most useful application of nesting is to list synonyms within parentheses using the Boolean operator OR, and combine these in a search with other concepts.

Example: (therapy OR treatments) AND schizophrenia

Field Searching specifies where a database will search for keywords in order to narrow and make search results more specific. Here is an example of an Advanced Search in a database:

To the right of the empty search boxes are drop-down boxes. The default selection is ‘Select a Field (optional)’. When left alone, the database searches for keywords in a few pre-determined places (the article title, subject headings, and abstract to name a few). If keywords are found in those areas it is likely an article will be relevant.

The drop-down boxes provide the option to search for keywords in specific locations. In the above example, the drop-down box to the right of ‘capitalism’ is set to ‘TI Title’. The database will search for articles where ‘capitalism’ is in the title, ignoring any that do not.

Limiters are additional parameters that a database can search for in addition to keywords. The limiters available depends on the database, but they can commonly be seen on the left after a search has been run, or underneath the search boxes on a database’s home page. Here is an example of what they look like:

Limiters are an important step in narrowing down a search to only the most relevant results. For example, you can limit to see only articles with Full Text Available, to see only Peer Reviewed Journals, or to specify a date range for when the article was published.

Truncation and the use of Wildcards are ways to expand your search by having the database include variations of word endings and spellings for your search terms.

They are especially useful when you are researching a topic where there are alternate spellings (such as variations between American and British spellings), or where your topic makes use of words where there can be both singular and plural endings, or word variations where there can be multiple forms.

To use truncation, enter the root of a word and put the truncation symbol, which is an asterisk (*) in most databases, at the end. The search engine will then search for any variant form that begins with that root word. Take care exactly what root you use as your search term, in case there might be wildly unrelated words that can be made from it which have nothing to do with your topic.

Example: child* will bring back results including: child, childs, children, childrens, childhood

Wildcards are when you replace a letter in your search term with the database’s wildcard symbol, often a question mark (?). This is useful for asking the search engine to find spelling variants, as the database will find results containing words with any letter in place of the symbol.

Example: colo?r will bring back results containing either the word color or colour as results.

Phrase searching is one of the most precise search techniques. When you enclose multiple words within quotation marks (“), you tell the search engine that you want only results with those words right next to each other, in that exact order.

This is a good technique to use when you are searching for a ‘term of art’ (i.e., a term, in this case, one containing multiple words, that has a specialized meaning in a particular field or profession).  In other words, everyone when communicating about that topic uses that exact phrase. Examples include “return on investment,” “peer tutoring,” or “myocardial infarction.”

Another example of when using a phrase search would be useful is when you are seeking something like a book or movie title, or someone’s name, such as “Shakespeare in Love,” “Of Mice and Men,” or “Steve Jobs.”

Proximity searching is an advanced search technique which allows you to search for two words that occur in the document within a certain number of words from each other. The operators and syntax for this type of searching vary between databases, but involves typing a proximity operator and a number between two search terms. For example, the search (tax OR tariff) N5 reform would return results where either the word tax or the word tariff, are found within 5 words of the word reform.

Other examples:
oil W3 (disaster OR clean-up OR contamination)
(baseball OR football OR basketball) N5 (teams OR players)

Below are guides to creating a proximity search in particular databases:

• EBSCO databases (OneSearch, Academic Search Premier, etc.)
• ProQuest databases (ABI Inform, ProQuest Dissertations & Theses) – found under “Operators, fields, and special characters”
• Elsevier (Scopus, Science Direct) – guide found under “Operators” section
• Nexis Uni