Boolean Operators are a set of fixed words, AND, NOT, and OR, that are used in most search engines. These words have specific functions in the search process. The easiest to describe is OR. When OR, in all caps, is placed between two word in a query, the engine will look for any occurrence of either word. OR expands the results list. The search engine is looking for either topic. In a way it is committing 2 searches, but putting the results in one list. AND, on the other hand, is used to narrow the results. When AND is placed between both words the search engine is looking for all occurrences where BOTH terms are present in the same page. So, if a website only has one of the terms, it will not be listed in the results page. AND narrows the results to have BOTH terms present. The other fixed term is NOT. NOT simply removes pages that have that term. So, the search engine will find all occurrences of the term, but then remove those that have the second term, the term listed after NOT. In Google these operators can be replaced by math symbols. AND is replaced with the plus sign, because you are adding a required term. NOT is replaced with the minus sign, because you are subtracting terms from the results. And OR can be replaced by a vertical line.
Another comment about Boolean operators and search engines is that you should always check the “help” or “tips” on the search page to know if the search automatically inserts AND or OR between your terms. Google automatically assumes AND between all search terms.
Proximity Searching is something that also can help narrow down your results. With Proximity searching you can look for terms that are NEAR each other or are WITHIN so many words of each other. NEAR returns results for the words, in any order, within some number of words of each other. WITHIN returns results for the words, in the order stated, within some number of words of each other. By stating NEAR5 or WITHIN5 you want the search terms within 5 words of each other. For example, an article about the death penalty, may have sentences that state the “penalty for such a crime is death.” So this sentence would be found by <death NEAR7 penalty>, but would not be found by the phrase search <”death penalty”> or <death WITHIN7 penalty>.
Proximity Searching is not used in our WorldCat catalog, but is available in our EBSCO hosted databases [N7 or NEAR7] and in ProQuest [NEAR/7 or N/7]. In ProQuest, WITHIN is replaced by PRE. In Google the wording is AROUND(x) [death AROUND(7) penalty].
A thesaurus is a book typically used to find synonyms or antonyms for known words. When using a search engine, it is often beneficial to look up other words, other keywords, because you want to find ALL the relevant materials. Many search engines have built in thesauri that can help you find the right words. Many thesauri are built around the idea of controlled vocabulary. What that means is that when you look for your word in a thesaurus, the returns will not be all the synonyms of the word, but will be words chosen by librarians, the Library of Congress or some other association, that are used in place of all the synonyms. These terms then are standardized and are used to tag articles and books and thus keep related materials connected by the controlled vocabulary. This can save time when researching and can produce better results. If you were searching for some illness, would you just enter “illness” as a keyword? You could and you would get some results. If you expanded and searched for “illness OR sickness” you would return even more results. But, by going to the thesaurus you may find that academic articles for your “illness” are really found under the controlled term of “disease” or “contagious diseases”. A thesaurus will help improve the accuracy of your search.
The same idea is applied to subject headings. Subject Headings are assigned by various groups so that everything about the same subject is found together. The most common set of subject headings are those of the Library of Congress. Other examples are: MeSH (Medical Subject Headings) used in the health sciences and SEARS, which is used as a compliment to the Dewey decimal classification system.
So, where do you find the thesaurus or the subject headings? In WorldCat, the subject headings will appear on the right-hand side on a materials page. A second set of those subject headings will be found at the bottom of the page of a materials page. You’ll see them as “similar items”.
In our EBSCO hosted databases, after you choose which databases to search, you can find “subjects” listed across the top of the page. Pick which thesaurus is appropriate for your research. The “Subject Search” in the EBSCO hosted databases searches the Library of Congress subject headings and some of their own creation.
In ProQuest you will have to go to the “advanced search” page to find the thesauri. Just above, and to the right of the top search box is a link to the “Thesaurus”. Pick an appropriate thesaurus and search for terms. The “subject headings” used in ProQuest appear to be LCSH. To find the actual “subject headings” you will again need to go to the “advanced search” page. Under “search options” (found BELOW the boxes), there is a “subject headings (all)” box and “look up subject headings (all)” hyperlink.
Our other databases don’t necessarily use thesauri or subject headings, but will often have some sort of “topic” to pick from. And this will narrow your search to an appropriate field.
One of the best search techniques then is to find the proper subject heading and search within that for one or two of your keywords. What you end up with is a Subject Search with AND and a keyword. This will require at least two boxes in most advanced search pages.
While searching all the databases simultaneously in WorldCat is possible, if you “add” all the databases, it may not return all the right material. As you notice, the subject headings and the Boolean operators are all a little bit different in each database. So, to be sure you are getting all the right material, be sure to search each of the databases separately. Save your search query and enter it in each database. You may find that you need to alter your search query to match to structure or subject headings of the database.
For most lower division work, the “search all databases” in WorldCat is probably just fine. For upper division work and for Master’s level work, you really should be searching the individual databases for the most relevant work.