Tackling Information Problems (TIP): Create and perform effective searches

Boolean logic refers to the logical relationship among search terms, and is named after the 19th century mathematician George Boole. It consists of three primary 'logical operators':
OR, AND, and NOT. Each operator can be visually described by using Venn diagrams, as shown below.  

AND

Use AND to narrow a search and retrieve records containing all of the words it combines,
for example cats AND dogs will only find records containing both these words.

OR

Use OR to broaden a search and retrieve records containing any of the words it combines,
for example cats OR dogs will find records containing cats only, dogs only, or both words.

NOT

Use NOT to narrow a search and retrieve records that do not contain the term following it,
for example cats NOT dogs will find records that contain cats, but will not contain the word dogs.

Phrase searching means searching for two or more words as an exact phrase.

Unless you specify otherwise, most databases will assume the AND operator, which means that all words must be present for a particular record to be listed in the search results, but not necessarily as an exact phrase. In other words climate change should get the same results as climate AND change.

When search terms are enclosed with double quotation marks (i.e. "climate change"), the search engine looks for words in the exact order.

Note that phrase searching is a very effective way of narrowing your search, especially if your phrase consists of two or more common words (such as social media or white house).  

If you include different operators in one search query, the database will combine them in this order: AND, OR, NOT.

To control the order in which your search terms get combined, you can use parentheses. 

Enclose search terms and their operators in parentheses to specify the order in which you want them to be interpreted. Information within parentheses is read first, then information outside parentheses is read next.

Examples
(cats OR dogs OR birds) AND "animal welfare" 
("global warming" OR "climate change") AND ("sea level rise" OR "extreme weather") 
("computer games" OR "video games") AND (children OR youth OR teens)

Keep in mind that truncation and wildcard symbols vary from database to database. Examples include: *, ?, !, #.

In library databases, every document is indexed to capture individual bits of information about the document, such as title, abstract, author, journal, publisher, etc. This indexing allows users to restrict their searches to specific ‘fields’ of the document record. 

In a field search you specify which field you want the database to search. For example, the search "video games" in the title field finds records that contain this phrase in the title. If you need publications from a particular author, the most efficient way to search is to select the author field. 

Which search fields are available and what they are called depends on the database. Usually, two-character abbreviations (field codes) are used, such as AU (Author), TI (Title), AB (Abstract), and SU (Subjects). Different field searches can be combined using Boolean operators. 

Search limiters (sometimes called filters) are powerful ways to focus your search results so that you don’t have to look through lots of irrelevant records to find what you’re looking for.

For example, many databases include items in foreign languages. If you only want English-language sources, you can use a search limiter to eliminate all other languages. Other common limiters/filters include

• type of material (e.g. articles, books);
• a certain timeframe;
• subjects.

Limiters/filters are often located somewhere on the database search page or results list as drop down menus or check boxes. Sometimes limiters are available on the Advanced Search page within a database. 

! Do not use the 'Full text 'limiter, if present. It prevents you from finding the full-text of the article you're looking for in other databases the university library subscribes to. 

If your search succeeded (i.e., you found a sufficient number of relevant sources), then you're not going to need to evaluate your search. But if your search failed, how do you go about? 

Modifying your search statement

Here's how you can modify your search statement:

To narrow your search:

• use other/more specific search terms; 
• limiting terms to particular fields (e.g. Title instead of All fields);
• reduce the terms linked by OR;
• add another key concept, linked by AND; 
• add limiters. 

To widen your search:

• use other/broader search terms;
• limiting terms to particular fields (e.g. Abstract instead of Title); 
• increase the terms linked by OR; 
• remove a key concept;
• remove limiters.

 There is no such thing as a perfect search! It may take a lot of searches to retrieve all the necessary sources. Approach your topic using as many search statements as you can think of.

Following up on reference lists
Another way to discover good sources is to examine the reference lists of relevant sources you already found. These can point you to important older research on the topic.

Citation searching
Many databases will let you search for sources that cite a known source. So if you have a good article, try clicking on the 'Cited by' or 'Times Cited' link to see newer sources.