Many databases have filters or limits you can apply to your search results. "Filters" and "limits" are often interchangeble terms that refer to different criteria you can select within a database to further narrow your results. In most databases, options for filters will appear on the right or left side of a results page after running a search.
For example, see this picture below showing just a few of the filtering options available in PubMed:
Filters are often applied while viewing the results of a search as a way to quickly exclude articles based on certain criteria. Every database has its own unique set of filtering criteria, but commonly used filters found in most databases include:
A way to ensure comprehensiveness in a search is by using truncation in your keywords. Truncation is an asterisk (*) used at the end of a root word to indicate that it may have separate endings.
For example, you may use “Child” as a keyword in your search, which will guarantee you see all instances of results with that word. However, the truncated version, “Child*” will account for any instance of a word that begins with the root word “child” such as “Childhood,” “Children,” “Childish,” etc.
| Truncated Keyword | Implied Keywords Due to Truncation | ||
| Child* | Child | Children | Childhood, etc. |
| Chil* | Chills | Chilled | Child, etc. |
Be warned, this method is not always helpful as it may retrieve unrelated articles if the word is truncated too soon. For example, if we had truncated the word at “Chil*” the results would now include anything having to do with children PLUS words like “chills” and “chilled.”
Another way to increase sensitivity of a search term is by using something called a wildcard. Wildcards, usually a pound (#) or asterisk (*), allow you to search multiple forms of a word where the spellings may differ within the middle, not necessarily the end like in truncation.
For example, to search for both instances of “woman” and “women” in a search, insert a wildcard where the letters differ. “Woman” then becomes “wom#n” and will retrieve results that contain both instances of “woman” and “women.”
| Keyword With Wildcard | Implied Keywords Due to Wildcard | |
| Wom#n | Woman | Women |
| Col##r | Color | Colour |
Note that the wildcard (# or *) can represent a value of 0 or 1. In the instance of the word "color," we may want to search the American and British spelling, in which case, there will be an extra letter to account for (as shown above). Using two pound signs indicates that we would like to see no letters, one letter, or two letters in this space.
Proximity operators, which look different in each database, allow a searcher to increase the sensitivity of a search phrase by searching different variations of a single phrase.
For example, you may want to search the phrase “animal therapy” but still pick up related phrases like “animal based therapy,” “animal assisted therapy,” or “therapy using animals.” By using a proximity operator of 3 within this search, we will be sure to retrieve results including all of these variations.
This chart uses “animal therapy” as an example phrase with the relevant proximity operators in red for each database.
| PubMed | Ovid | Cochrane | Web of Science | CINAHL |
|
"animal therapy"[tiab:~3]
|
(animal adj3 therapy)
|
(animal NEAR/3 therapy)
|
(animal NEAR/3 therapy)
|
(animal N3 therapy)
|
The table above uses a proximity of 3 as an example, but depending on the search, this number could be higher or lower. A good rule of thumb for choosing the proximity number (N) is below: