should break a topic or question down into separate concepts. For
example, if you want to find articles on the use of aspirin to prevent
stroke, stroke and aspirin are separate concepts.
work best if you search for articles on each concept separately and
combine those separate searches at the end of the process.
on any particular concept should take account of synonymous terms
(eg stroke, cerebral vascular accident, CVA etc
searching for the purpose of good quality research should cover both
defined subject headings (known as MeSH in medline) and textword equivalents.
article that is added to medline (and most other databases) is given
a number of defined subject-headings to describe the contents
of the article. On Medline this system is called MeSH (Medical
Subject Headings). An article may have more than 20
subject headings, which come from a Thesaurus of controlled terms.
For example all articles concerning stroke that are added to the Medline
database should receive the subject heading Cerebral Vascular Accident.
There is no subject heading of stroke. A subject heading search will
usually provide a fairly refined search where the term or terms you
have searched for are always in context.
thorough search should also look for textwords. A textword search
looks for a specific pattern of letters in the title, abstract or
subject-headings of references. A textword search on diabetes, for
example, will find all the articles that have this pattern of letters
in their title, abstract or subject headings. However, it will not
find articles containing the word diabetic. Wild-cards can
get round this problem by allowing variant endings on words. Unfortunately,
wild-cards differ from database to database. On OVID versions of Medline,
EMBASE and CINAHL use $ i.e. diabe$. On the Cochrane Library or Pubmed
use * i.e. diabet*
you have completed the searches on each concept the searches should
then be combined. Firstly, searches on a single concept should
be combined with
OR (eg stroke$
(textword) OR Cerebral Vascular Accident (subject heading)). Finally
searches on different concepts should be combined with
AND (eg stroke
searches AND aspirin searches) to get to your final result.
you have too many hits, a further concept could be introduced to narrow
your search down. Alternatively, most databases allow limits
to be applied to a search (for example by publication type, or age-group
a number of databases to choose from and a thorough search will include
more than one database. Most sources, such as Medline and CINAHL list
single journal articles. The Cochrane Library is different, offering
high quality systematic reviews which bring together high quality
controlled trials to provide a best picture of the evidence on a particular
a successful search be prepared to look at the articles you find with
a critical eye. To assist this process see the checklists provided
by the Critical Skills Appraisal Programme CASP