Knowledge syntheses involve systematically searching the literature. For example,
Systematic reviews of interventions require a thorough, objective and reproducible search of a range of sources to identify as many relevant studies as possible (within resource limits). This is a major factor in distinguishing systematic reviews from traditional narrative reviews (...)
Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0. The Cochrane
Collaboration, 2011. Available from http://handbook-5-1.cochrane.org/.
Systematic searching is:
We recommend developing the search strategy in one database before translating the search strategy to the other selected databases: This will make it easier to keep track of things. If you subsequently find terms in the other selected databases, you can then go back and add them to the searches that have already been developed.
It is recommended that you have your search strategy peer reviewed. For peer review criteria and critical appraisal search strategies, consult:
We also recommend running all the searches on the same day to make it easier to document the date in your manuscript.
Once you have your searches developed and you are ready to run them, you can the export the records from each database to an EndNote library, which you will keep for your files.
Keep track of the terms you will be using in your search strategy in whatever way works best for you. Below, we provide an example of a worksheet that can be used for this purpose. Depending on your research question, the list of terms can get quite long and can be difficult to manage if you are not recording them as you are finding them.
A subject heading is an assigned word or phrase used in some databases to uniformly describe a concept. Searching using this standardized word or phrase, instead of keywords, means you do not need to worry about synonyms and spelling variations.
Example: The subject heading for cancer in MEDLINE (via PubMed) is the MeSH term Neoplasms. This means that all articles selected for indexing in MEDLINE that are about cancer at a general level will be tagged or indexed with this subject heading, or if the article is about a specfic cancer like breast cancer, with a narrower term (note: there is a time delay between the addition of records to MEDLINE and their indexing with MeSH terms, and some records will not be indexed at all).
How the subject headings are actually used in a database (if they're even available) depends on the platform you're searching, e.g., to use the subject heading for 'Neoplasms' in PubMed or Ovid MEDLINE:
Using MeSH in Pubmed (3 min 02)
Using Subject Headings in CINAHL (3 min 32)
Advanced Search on the Ovid Platform (with a focus on Ovid MEDLINE, using MeSH subject headings as well as subheadings) (13 min 25)
Health Sciences Library, McMaster University. (2014, October 16). OVID Medline - Part 1 - Starting Your Search [Video file]. Retrieved from https://www.youtube.com/watch?v=Qm2tuuxqftg#action=share
Health Sciences Library, McMaster University. (2014, October 16). OVID Medline - Part 2 - Refining Your Search [Video file]. Retrieved from https://www.youtube.com/watch?v=wtO-KdQRtUg&feature=youtu.be
Keyword (or textword) searching is when we search for words which we expect to find in the title, abstract, or author-defined terms of relevant articles; it is how we typically interrogate web search engines. Draw up a list of words or phrases related to each concept in your research question. When using this technique, you will need to be aware of synonyms and spelling variations.
Example: Keywords (or textwords) for cancer can include cancer / cancers / cancerous / neoplasm / neoplasms / neoplastic / tumor / tumors / tumour / tumours etc.
Note: Capitalize your operators as a matter of practice. In some databases, it does not matter whether you enter them in uppercase or lowercase, but others (like PubMed or Google Scholar) require them to be in uppercase.
Use parentheses to set the order of execution of the Boolean logic. Parentheses work in most but not all systems (e.g., they work on the Ovid, PubMed, EBSCOhost, ProQuest, Scopus, and Web of Science platforms, but they are ignored in Google and Google Scholar)
e.g., (chest OR thorax OR thoracic) AND (imaging OR radiographs OR radiography)