These guides are designed to facilitate self-study, or to accompany a librarian-led session on searching for information via the OvidSP databases.
Free text searching
Free text searching means searching for words and phrases that appear in certain fields in the database records. These fields always include the title and abstract of the article, and depending on the database can also include other fields such as subject headings.
The most basic type of free text search involves typing in a word or phrase into the search box and clicking on SEARCH. The database will return records where that exact word or phrase appears. You can make your search more flexible by using truncation, wildcard or adjacency symbols.
Using a truncation symbol (*) when free text searching
The truncation symbol (*) stands for one or more letters and allows you to search for all different forms of a word at the one time. It’s particularly useful for plurals.
e.g.
Instead of nurse OR nurses OR nursing
nurs*
Instead of pregnant OR pregnancy
pregnan*
Instead of therapy OR therapies OR therapist
therap*
The key to using the truncation symbol is to place it after the shared root of your word. The root is the group of letters that all forms of the word have in common. You should also be careful not to truncate to a root that has too many forms to be useful:
e.g.
If you search with therapy* you will not get therapies or therapist
If you search with therapi* you will get therapies or therapist but not therapy
If you search with therap* you will get all three possibilities as they all share the root therap…
But watch out…
If you place the * sign too far back and search with ther* you will get therapy, therapist, therapies…and also therapeutic, there, therefore, thermal, thermometer, thermogenisis, thermostat……..
Using adjacency (ADJ) when free text searching
Adjacency is very useful when searching using free text terms as it allows you to specify that words need to be found near each other in the document but that they can also be in any order. You can specify how near by using a number. This helps your search in two ways:
1. It allows you to search for different phrases at the same time.
e.g.
asthma ADJ inhaler The words must appear right next to each other, although they can be in any order (asthma inhaler or inhaler asthma)
asthma ADJ3 inhaler The words must be within 3 words of each other (in any order) – “an inhaler for asthma”, “an asthma inhaler”, “using an inhaler for moderate asthma”
You can combine * and ADJ for even more flexibility:
e.g.
asthma$ ADJ3 inhaler* would include:
“asthmatics use inhalers”
“inhalers for moderate asthma”
“use of an inhaler by an asthmatic”
2. It also works on the principle that words that are near each other are more likely to be related.
e.g.
lung adj3 cancer would include:
“lung cancer”
“cancer of the lung”
“the cancer spread to the lung”
But would not include articles where other lung diseases were being discussed and the word cancer occurred in an unrelated sense.
Using a wildcard symbol (?) when free text searching
The wildcard symbol (?) stands for a possible letter and is particularly useful when searching for words with British and American spellings.
e.g. colo?r = color OR colour
Unfortunately, the wildcard symbol must have at least two letters in front of it so is no use for searching for words like paediatric/pediatric, haematology/hematology, foetal/fetal. In these cases you must remember to include both forms in your free text search:
e.g.
haematol* OR hematol* When searching for instances of the words haematology or hematology or haematological or hematological or haematologist or hematologist.
Combining symbols to make up a search string
It is always advisable to have scrap paper to write down your search terms and work out free text search strings on until you become confident at searching.
Write down your key words and try to think of all possible synonyms and combinations, and then use the free text symbols, and the AND and OR linking terms to produce a search string.
e.g. A search string for the concept pressure sores
Possible synonyms for pressure sores: pressure sore, bed sore, bed sores, decubitus ulcer, decubitus ulcers, pressure ulcer, pressure ulcers
All these terms can be expressed by the search string:
(pressure or bed or decubitus) ADJ (ulcer* or sore*)
Note the use of brackets to show that one of the terms inside the first set of brackets should be adjacent to one of the terms in the second set. It could also be written as:
pressure ulcer* or bed sore* or pressure sore* or decubitus ulcer*
Another example:
A search string for the concept lung cancer:
Possible synonyms for lung: lung, lungs, pulmonary
Possible synonyms for cancer: cancer, cancerous, tumour, tumours, tumor, tumors, neoplasm, neoplasms, malignant, malignancy
Using adjacency to relate the two terms:
(lung* or pulmonary) adj3 (tumo?r* or neoplasm* or malignan* or cancer*)
Note the use of the wildcard symbol to stand for the possible “u” in tumour (vs tumor) and the “3” after ADJ so that phrases such as “cancer of the lung” are included.
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Written by Seona Hamilton. Please contact your local or subject librarian for training in literature searching and using online databases.
Last updated June 2011