Databases typically contain their own controlled vocabularies that can be found within the databases themselves, but there are also print resources available. These controlled vocabulary resources can be found on the fourth floor unless otherwise noted.
Boolean operators are attributed to English mathematician George Boole, who, in the 1800s, devised a mathematical language to define the relationships between values or words. The common Boolean operators AND, OR, and NOT can be used in bibliographic research to combine search terms or strings (multiple search terms) to either expand or narrow searches.
Use AND to narrow results. Combining meteor AND "International Space Station" will retrieve items that contain both concepts, but exclude items that contain only one or the other.
Use OR to expand results. A search for meteor OR "shooting star" retrieves items that contain either one of the concepts. The OR operator works best with similar terms, such as the academic and informal versions of one concept (example: "meteor" and "shooting star").
Use NOT before a search term to exclude all results that contain the specified term – very narrowing!
Most databases offer advanced search forms that allow you to combine concepts using Boolean operators. Many contain dropdown lists that default to basic search combinations or let you choose from among supported operators.
Effective, efficient searches retrieve the items that are most closely matched to the research concept, reducing the time that you will have to spend evaluating the results.
A big part of finding relevant information is 1) knowing where to look and 2) having good keywords and search terms to use in your search!
Before beginning your search, take a moment to determine the focus of your topic and what terms might be used to express that focus. Using a tool like a concept map might help you narrow your focus and identify keywords. See an example concept map below:
Once you've determined your focus and keywords, you then need to decide where to begin your search.
Choose a resource based on its scope - subjects, time frame, and types of materials that it contains - and then compose searches that make sense in the context of the tools. This may take a little bit of time to learn, but doing so will ultimately save you lots more time in evaluation.
Remember that each tool is different, but you can find out which search strategies are supported by using the Help provided in the tool. Even Google has Help! In addition to the Help, many Advanced search forms contain search tips, and many will list the supported search strategies.
Sometimes finding features in a website or database can be tricky, but remind yourself to Read Everything on the Screen! Look around at the menus and links in each tool - at the top and bottom of the window, along the side, and embedded within the text, often as information or question-mark icons.
Remember to pay particular attention to the subject terms, keywords, and terminology used within the articles and resources that fit best with your own research. You can use these terms to modify your own searches to find more pertinent items.
Controlled vocabulary or subject searching is a powerful, precise way to retrieve all of the items in a database that are specifically about a particular subject.
Controlled vocabulary searches involve two parts: identifying a valid controlled vocabulary term, and searching for that term in the database's subjects field.
The Library of Congress Subject Headings are the controlled vocabulary for our library catalog. Controlled vocabularies are sets of terms that have been predefined as standard within a certain field. The Library of Congress Subject Headings are used by the Library of Congress and most academic libraries -- including ours -- to describe indexed materials.
Most non-catalog databases contain their own controlled vocabularies, often called thesaurus or subjects. Consult the Help in the tool to find out what the controlled vocabulary is called, and how to search for it.
What makes controlled vocabulary/subject searching useful is that ALL of the items in a database that are specifically described with a term can be retrieved with a controlled vocabulary search. This differs from a keyword or "all-fields" search, because keywords can appear in the item's title, description, full-text, etc., and may not fully represent the character of the item, whereas the subject headings appear in one specific field of the item's record, and represent the essence of the item. To simplify: keyword search results contain the terms; controlled vocabulary searches are about the terms.
Perform a controlled vocabulary search in the Evans Library catalog by locating a valid term (it will be hyperlinked) on the Library of Congress website, entering that term in the catalog, and then choosing to search in the Subject field. Click the images below to get started!
Many bibliographic discovery tools include options for refining search results to those that are most pertinent to your need. Depending on the tool, you may be able to narrow your results to a specific publication date range, content type, language, or author, among many other options. Limiting results keeps you from getting that lost in space feeling from scrolling through too many items, and it helps to bring the types of results that you want to the top of the list.
Most searches, especially in Internet search engines, retrieve more results than you can scroll through. Tools that offer the option of refining your searches to items from scholarly or peer-reviewed publications can make finding the best academic resources a lot easier.
Limiting to items from specific subject areas or that are published within a specific date range also helps to eliminate information that is not exactly pertinent to your particular research.
Many bibliographic discovery tools support the concept of nesting, or grouping related concepts together in parentheses to clarify the order of the search. The grouped concepts are searched first, just as in mathematical equations.
Nesting is quite useful when searching for very closely related concepts that could have variations in terminology. The search engine will not know to look for both variations unless you specify them, and nesting the variations with OR clarifies the relationships among the keywords.
A search for "space travel" AND ("human factors" OR ergonomics) will retrieve items that contain either human factors or ergonomics first, and then add the term space travel, to end up with results that contain either human factors and space travel or ergonomics and space travel.
Nesting does not necessarily expand or narrow, but clarifies the order of searches.
Many databases will automatically nest keywords joined by OR. You may notice that when you use advanced search forms to combine keywords with Boolean operators, the resulting search string contains parentheses - the keywords joined by OR are the nested keywords.
Truncation, or wildcarding, is the use of a symbol, typically an asterisk, at the beginning, end, or within a root word to take the place of one or several characters. This means that you can use the truncation symbol to retrieve several variants of a search term at once -- less typing!
Some truncation, wildcard, or substitution symbols take the place of one character only, while others can replace any number.
Some examples are astron* to retrieve astronaut, astronautical, astronomy, and astronomical, and travel?er to retrieve traveler or traveller.
Some tools use autostemming, which automatically searches for every ending or format of a word.
Truncation expands searches.
Using truncation allows you to retrieve variations in spelling that you have not even thought about!