Searching systematically: literature searching in a systematic way

A typical search uses both

Subject Headings (Thesaurus)

• MeSH is is the National Library of Medicine (NLM) controlled vocabulary/dictionary of terms used when indexing articles in PubMed and Medline. 
• MeSH subject headings are used in Cochrane 
• CINAHL uses MeSH headings and also CINAHL subject headings
• Emtree is the controlled vocabulary or thesaurus used in Embase (Ovid) and is very similar to MeSH.
• APA Thesaurus of Psychological Index Terms are used in PsycINFO

AND

KeyWords

• Free text or keywords
• Alternative words /Synonyms
• Alternative spellings
• Singular/Plural terms

Search techniques (see below) are also available in all databases. These techniques can be used when creating a search strategy. 

Search techniques have been developed to make it easier to search the databases and to find the most relevant articles for your search topic.   The reason is that the databases are very big,  there are over 38 million citations  in PubMed,  over 31 million records in Medline,  over 4 million records in CINAHL,  over 40 million in Embase. 

The search techniques allow you to more easily search and navigate the databases. 

The Boolean operator OR is used to search for all the potential keywords for one topic or element of the framework. 

The Boolean operator AND is used to combine different concepts or parts of a framework (fewer results)

See also this Boolean Operator Video  

Every article added to the databases includes a number of Subject Headings which relate to the content of the article and the type of study.  Each Subject Heading  has a specific definition.  Subject headings are reviewed yearly and can be changed or amended depending on changes or developments  in the subject.  

Use quotation marks before and after a phrase or words to search for a particular phrase or name.  Some databases will automatically search as a phrase, but if  you are unsure, you can use quotation marks. 

Also be aware of stop words,    if you are searching the term health and safety,   the word and is a stop word and the database wont search it,   so if you are searching for the exact term health and safety,  you should use quotation marks, so you should search  it as  "Health and Safety"

Every database allows the use of ".." for phrase searching.

Truncation - uses a symbol to replace a letter or letters in the middle or, more often, at the end of a word.  Depending on the database the following symbols can be used.

• Asterisk *   
• Question mark ? 
• Dollar sign $  

Truncation is used most often to search for plurals and alternative spellings.

Searching using a proximity/adjacency operator means that you  can search for terms within a certain number of words of each other next to, near to, in a sentence or paragraph or page section. 

The search terms will be in the same proximity or close to each other with a certain number of words in between them. Using proximity or adjacency narrows the focus of the search,  and limits irrelevant results. 

A short summary of common search terms which can be used when searching HSE Library databases on the Ebsco and Ovid Platforms.

Search Filters are pre-made search strategies that can be used for a complex search, for example where you are looking at Systematic Reviews or RCTs.  These search filters can be copied and pasted into the database as if you are adding a new concept, and the results added to the existing search.   There is a range of search filters available: some are used to limit to particular study types and others limit to a clinical topic such as diagnosis or etiology. Using a search filter can save time and effort. 

Note:

Check before using a search filter that the filter is validated, that it is produced by experts and that it will suit  your search. 

Search filters are normally designed to suit the database or platform, so a filter designed for use in Medline(Ovid) will be different to a filter designed to be used in PubMed.    

You can use more than one search technique on the same search line.   See some examples here. 

You can test the search strategy by looking  to see if  well known articles or reviews are appearing among the results.  You may need to edit your search by adding in or removing search terms.