When performing a simple search in a search engine like Google it is easy to type in a phrase or sentence to explain what you need. When you type a phrase such as "how does a car work?" the search engine will use algorithms to determine what it thinks you meant, sometimes with mixed results. In order to locate the most relevant results quickly, particularly when you start working in specialized databases, it is important to break down your research question into its key concepts which can then be used as keywords in a database search.
Example: How does caffeine affect the memory of college students?
To find the keywords in the sentence, you will first eliminate all the words that do not provide any meaning to the sentence, so the remaining words will be considered your keywords to use in a search for information. In this sentence, words like “how” and “does” will be eliminated so to leave the remaining words "caffeine," "memory," and "college students" to become our keywords for finding meaningful search results.
One way to limit a database search is to use Boolean operators; words you can add to a search to narrow or broaden your search results. They are AND, OR, and NOT. You can usually find these words in the advanced search query area of a database. And will narrow your search.
AND –If the main idea contains two or more ideas, you’ll want to use AND to combine those terms in your search statement. This is what automatically happens in search engines such as Google and Bing unless you tell them to do something different by using OR or- NOT.
For example, if you are interested in freshwater fishing, you would enter the terms “fish AND freshwater.” Your results would then include records that only contained both of these words.
The green overlapping area in the diagram above represents the results from the “fish AND freshwater” search.
OR – If the main idea has several synonyms, use OR to combine them. Most search tools search for all terms using AND by default, so you need to use the term OR between terms to let it know you want to find any of the terms not results with all the terms.
For example, if you are interested in finding information on mammals found in the Atlantic Ocean, you could enter the terms “whales OR dolphins”. The circles represent the or search. All of the records that contain one or another or both of your search terms will be in your results list.
NOT – If the main idea has a common use that you want to exclude, use NOT to exclude that word. For example, if you were looking for information on all Atlantic Ocean fish except Bluefish, you would enter “fish NOT bluefish.”
The larger green circle represents the results that you would retrieve with this search.
Special characters can be used in keyword searches to create a more specialized search. The main special characters that are used are quotation marks, the question mark, the asterisk, and parentheses.
Use Quotation Marks for Phrases
Put quotation marks around any phrases among your terms so that the phrase is what’s searched for, rather than the separate words. Using quotation marks around “Common cold” instead of just typing common cold without quotation marks is a good example. Without those quotation marks, just think how many sources Google or other search tools would find to waste your time on things that have nothing to do with the sniffles.
Use Wildcard and Truncation Symbols to Broaden
Consider using the wild card or the truncating symbol to find variations of a word. For instance, the wildcard symbol in wom?n finds both woman and women, and the truncating symbol in mathematic* finds mathematics, mathematically, mathematician, etc.
Use Parentheses with Multiple Operators
When a search requires multiple Boolean operators (AND, OR, NOT, or their symbols), you must use parentheses to group the appropriate terms with each Boolean operator. The resulting statements connect terms, remove terms, and organize search terms in ways that result in complex and precise searching.
Never use parentheses unless you are using multiple Boolean operators.
