When searching systematically it is important to use both keywords and subject headings as well as filters and other advanced searching elements. Here is an overview of the process:
The sources you search will depend on your project. Here are some sources to consider.
If you are doing a systematic review, explore protocol databases to ensure that no one else is currently working on the same project.
To find as many relevant studies as possible, you'll need to include as many relevant keywords as possible in your search. Let's examine an example research question.
Do e-cigarettes assist young people with smoking cessation?
If we search in a database (say, PubMed or FiNDit) using some of the words in this question (e.g. e-cigarettes, or smoking cessation), we can use words from the results to start to compile a list. You can also use an online dictionaries or encyclopaedias to search for synonyms. It's OK if your initial list of keywords isn't perfect to begin with or changes over time. Feel free to add or remove words from your list as you get more experience with searching.
Concepts and Keywords (Initial brainstorm)
|Giving up smoking
|Digital Vapor Cigarette
|Juul [brand name]
Review the video below from Ohio University Libraries, which shows you how to gather and combine keywords for an effective search.
Subject headings are terms assigned to article records which describe an article's (or book's) content. Subject headings are usually assigned by the database itself (not the author), not the author of the work. As databases contain content from many countries, contexts, and disciplines, subject headings are a useful way to provide consistent language to describe contents.
As an example, let's look at the subject heading Ability in the database Psychology and Behavioral Sciences.
|Used for the similar terms
(plus many more)
In databases such as Google Scholar that don't have subject headings, a person could search for the word "Ability" and only find articles that match the one word Ability. However, if someone searched for the word Ability in the Psychology and Behavioral Sciences database, they would also get articles that focus on concepts of Aptitude, Proficiency, Skill and Talent, which are very similar concepts to Ability. This means that you would get more relevant articles by using subject headings in addition to keywords.
Narrower terms are concepts that sit underneath the main subject heading in a hierarchy. In the table above, you can see that Athletic ability and Academic ability are sub-types of ability. To learn more about subject headings, view the video below or the Learn More section on this page.
Boolean operators form the basis of database logic. They connect your search words together to either narrow or broaden your search. Let’s consider AND, OR, NOT.
The ‘AND’ operator
Use AND to connect different concepts. Using AND directs the database to show records that include all the search terms that were used in the search. All search terms will be listed in the results. The more search terms connected by AND, the more specific your search will be and fewer records will be retrieved. Be aware in some databases AND is implied.
The ‘OR’ operator
Using OR broadens the search to include all records that contain any terms used in the search. This type of search links like terms or synonyms together. Each time you add another term with the OR operator you are potentially increasing the number of records that will be retrieved. You can use OR to search for synonyms, alternate spellings, or abbreviations.
The ‘NOT’ operator
Use the NOT operator to exclude certain words from your search. Using NOT narrows the search by excluding specific terms. Be aware that this is a powerful search operator and may also exclude important records.
Some databases assume that a string of words will be searched as a phrase whereas others will search on each individual word. Phrase searching tells the database to look for two or more words in the exact order they are entered. Use the quotation marks "" to enclose a phrase.
Example: Searching for "climate change" finds this exact phrase, excluding irrelevant results about 'change'.
Watch this video from QUT on phrase searching.
Proximity or adjacency operators allow you to locate one word within a determined distance from another. Words that are close to each other are more likely to be related than those that are further apart. Using proximity operators will limit your search returning a smaller, group of results. Proximity operators differ between databases. Check the database help screens to find out which operators are appropriate to the database you are using.
Watch this video on proximity searching from QUT:
Use truncation symbols to look for the root or stem of a word. The most commonly used truncation symbol is the asterisk *.
Example: The search creat* will retrieve create, creates, creator, creative, creativity etc.
Be careful to use a word stem that relates to your meaning.
Example: The search polic* will return policy and policies, as well as police and policing.
A wildcard symbol is used to substitute for a character either within a word or at the end of a word. This symbol is particularly useful for American or British variations or when you’re unsure about the spelling of the word.
Example: The term organi?ation will find both ‘s’ or ‘z’ spellings.
Truncation and wildcard symbols vary between databases and internet tools, so check the help section of each database.
Watch this video from QUT on truncation and wildcards:
Nesting search terms within parentheses () controls the logic of the search so you can group synonyms in sets. The part of the search within the parentheses is performed first.
Example: The search (“respiratory tract infection” or bronchiolitis) and management finds articles about the management of both respiratory tract infections and bronchiolitis.
You may also use limiters to narrow your search. This is often best done in the results screen to increase the relevancy of results after a comprehensive search. Limiters include:
Search engines such as Google have their own limiters including: