Module 3. KEYWORD SEARCHING Using Boolean Operators

Objectives - On completion of this module, students will be able to:

• develop a search statement using keywords and synonyms;
• identify the fields searched by keywords;
• apply Boolean operators in keyword searching

 

Introduction -

Keyword searches are 'free-text' searches. This means the term you enter is searched in multiple fields in the database records. By using Boolean logic, you are able to combine terms from any of these multiple fields to keep your searches focused.

 

Example: Searching 'rabies' as a keyword means the term is searched simultaneously in

all the highlighted fields below:

 

A. Steps in keyword searching -

 

1. Begin by developing a search statement for your topic.  A search statement is a sentence or two stating clearly what information you need to find.
   Example: What are the symptoms of Cushing's disease in dogs?
   
2. Select significant or unique words from your search statement as keywords.
   Example: symptoms; Cushing’s; dogs
   
3. Combine the keywords using Boolean operators (AND, OR, NOT).
   (For this search statement, the correct operator is AND, as explained below).
   Example:  symptoms AND Cushing’s AND dogs
   
4. Use synonyms (words with similar meanings) with your keywords to expand your search. 
   Example: (symptoms OR signs) AND (Cushing's OR hyperadrenocorticism) AND (dogs OR canine)

Note that synonyms in item #4, are grouped or "nested" within parentheses. Keywords within parentheses are searched first; then the results 'AND-ed' together.

B. Linking keywords using Boolean Operators (AND, OR, NOT) -  

1). Linking with "AND" -

a)     Normally we think of "and" as expanding a concept. For example, "I like dogs and cats" refers to more animals than "I like dogs".

 

b) However, using the Boolean 'AND' between terms means both keywords must be present in the record. That is, 'AND' finds only items that contain both words (or phrases), thereby decreasing the number of results.

 

c)     When to use 'AND': Too many results? Narrow the search by making it more specific using "and." 

Example: dogs AND cats - will find only items that have both those words; dogs AND cats AND gerbils - will narrow results more, finding only items that have all three words somewhere in the record.

2). Linking keywords with "OR" -  

a)     "I'm getting a dog or a cat," describes alternatives, (i. e., one or the other, but not both).

b)     However, the Boolean operator 'OR' (dog OR cat) will include all references to dogs as well as all references to cats. "OR" is used to broaden a search.

c)     When to use 'OR': Too few results? Think of synonyms for each keyword. "OR" the keywords and synonyms together to increase your search results.

 

3). Linking with "NOT" -

a)     The Boolean operator ' NOT' is used to eliminate an unwanted topic.

b)     When to use NOT: Use 'NOT' only when retrieving the maximum number of items is less important than excluding a specific topic. Because "NOT" may exclude some pertinent articles, it is used with caution.

Example: 'snakes NOT turtles' will exclude -

all items about turtles, as well as

all items mentioning snakes and turtles in the same article

 

Summary of Module 3 -

Keyword searching is comprehensive because terms are searched simultaneously in multiple fields in the database records.

 

Keywords are chosen or developed from your search statement which is developed from your topic.

 

Boolean operators (and, or, not) are used to connect keywords to expand or narrow search results.

 

Mini Test on Module 3 -

1. Keyword searches are effective in searching article databases, but not library catalogs.
   True
   False
   
   
2. Writing a search statement can be useful in developing keywords.
   True
   False
   
   
3. Joining two or more keywords in a search with ‘AND’ will expand your results.
   True
   False
   
   
4. Joining two or more keywords in a search with ‘OR’ will decrease your results.
   True
   False
   
   
5. When you use the Boolean operator ‘NOT”, you may exclude some useful  results.
   True
   False
   
   

Module 4 is about searching in specific fields.