Searching

Advanced searching and controlled vocabulary

Effective searching involves more than simply putting keywords in a search box. Systematic review search strategies need to be crafted in a manner that aims to ensure reproducibility and that no relevant articles are missed.

Identifying your review's key concepts and their synonyms or related terms should be your first step. Find more information about that process here: How do I identify my search terms? (Library Research Skills Tutorial).

Using search operators like AND and OR can drastically improve the quality of your search results. You can find more information about using search operators here: How do I combine my search terms? (Library Research Skills Tutorial)

Other, more advanced search techniques can be used to search for specific phrases, for keywords at a specific distance from others (adjacency searching), for spelling variants (wildcard searching) and for variant endings (truncation), amongst others. Individual databases often provide information on how to use these techniques in the “Help” sections of their websites. The way these search techniques are applied can vary from database to database. As a result, each database you search will require its own unique search strategy.

Another important aspect of databases to consider is their use of controlled vocabulary. Databases often use a specific set of words and phrases to index their articles. This set of words and phrases is known as a database’s controlled vocabulary. Controlled vocabulary can be extremely helpful for finding all of the articles on a specific topic, even if the articles themselves use different wording to describe a concept. As a result, using a database’s controlled vocabulary can help ensure comprehensiveness in your search, especially in cases where you have not been able to identify all possible synonyms for a key concept.

One good example of controlled vocabulary is the use of Medical Subject Headings (MeSH) to index articles in PubMed. Check out this PubMed help guide to learn how to Search PubMed using the MeSH database.

Both controlled vocabulary terms and keyword searching should be used in systematic review searches. Doing so should help prevent your search from missing articles in the database that have yet to go through the indexing process.