Use the following techniques when entering your search terms into databases to help you find relevant results:
|Command||" " vertical quote marks (be careful with copy and paste)|
|Use||To enclose a short phrase|
|Effect||The search will find the exact phrase|
|Command||* asterisk (in most databases) A few databases truncate word stems automatically.|
|Use||On the end of a base/root word|
|Effect||The search will find all the different word endings|
|Example||teen* finds teen, teens, teenage, teenager, teenagers, teenaged|
Use between search terms describing one concept to find results containing any of the alternative terms.
Using OR broadens your search.
Example: "vitamin C" OR "ascorbic acid" will find records with one of these terms or both.
Use to combine your concepts to only find results containing all the concepts.
Using AND narrows your search.
Example: "pain management" AND "mobile applications": both terms must be present in the results.
Use to exclude terms from your search results.
Using NOT narrows your search.
Example: diabet* NOT gestational: records that have the term "gestational" are excluded from the results.
When using a combination of AND and OR operators in a search, enclose the alternative terms or synonyms in parentheses.
Example: ("vitamin c" OR "ascorbic acid") AND (cold OR flu OR influenza)
See Search strings for more details.
PubVenn - explore PubMed using venn diagrams to find the relative size of the citation set for each term as well as how those sets interact. These diagrams may help users visualize how complex searches work.
This search technique is occasionally helpful for finding relevant results:
|Command||N# (EBSCO) ADJ# (OVID) W/# (Scopus ) Note: # is a number|
|Use||Links two terms together (where a relationship between the 2 elements is inferred)|
The search will find the first term only if it is located within a maximum number of words of the second term.
The order of the terms is not important.
EBSCO: (diabet*) N6 (foot OR feet)
OVID: (diabet*) ADJ6 (foot OR feet)
Scopus: (diabet*) W/6 (foot OR feet)
Proximity searching narrows your search
Most databases have subject headings (controlled vocabularies) assigned to articles to describe what the article is about.
Examples of subject headings used in some key databases:
|Business Source Complete||Business Thesaurus|
|CINAHL||CINAHL Headings; MeSh|
|PsycINFO||PsycINFO Thesaurus; MeSh|
MeSH is a well-known thesaurus of biomedical and health related information.
You will find MeSH in the Medline database, via EBSCO, OVID, PubMed or Web of Science.
Search Mesh headings using MEDLINE (EBSCO)
The Yale MeSH analyzer (by the Yale University Library) allows users creating a MeSH analysis grid using PubMed. Use it to identify new search terms and the missing articles from PubMed.
Video tutorial: Yale MeSH Analyzer (7.39 mins).
A new OVID search tool allows users to:
Video: Ovid Search Builder (9.28mins).
Snowballing refers to using the reference list and the citations of papers you have selected for your research to identify additional papers. It involves looking backwards and forwards to identify other papers that may be relevant. This allows capture of papers that may not appear in search results due to keywords or terminology not used or indexed in a database.
Find citations for the papers in Scopus, Google Scholar or any other resources. Citation analysis tools are available in Scopus.
Other tools may also be used for citation analysis (e.g. for finding themes, how articles cite each other, and gaps):
Ecar, M., da Silva, J. P. S., Amorim, N., Rodrigues, E. M., Basso, F., & Solda, T. G. (2020). Software Process Improvement Diagnostic: A Snowballing Systematic Literature Review. 2020 XLVI Latin American Computing Conference (CLEI), 156-164. https://doi.org/10.1109/clei52000.2020.00025
Mourão, E., Kalinowski, M., Murta, L., Mendes, E., & Wohlin, C. (2017, 9-10 Nov. 2017). Investigating the use of a hybrid search strategy for systematic reviews. 2017 ACM/IEEE International Symposium on Empirical Software Engineering and Measurement (ESEM), 193-198. https://doi.org/10.1109/ESEM.2017.30
van Haastrecht, M., Sarhan, I., Yigit Ozkan, B., Brinkhuis, M., & Spruit, M. (2021). SYMBALS: A systematic review methodology blending active learning and snowballing. Frontiers in Research Metrics and Analytics, 6(33). https://doi.org/10.3389/frma.2021.685591
Wohlin, C. (2014). Guidelines for snowballing in systematic literature studies and a replication in software engineering. EASE '14, May 13 - 14 2014, London, England, BC, United Kingdom. https://doi.org/10.1145/2601248.2601268