Literature search for systematic review
Systematic and other kind of reviews: a short introduction
A systematic review is defined as “a review of the evidence on a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant primary research, and to extract and analyze data from the studies that are included in the review” (definition byTemple University Libraries). For the collection of relevant primary research a systematic search of literature is needed.
These basic elements determine a literature search for a systematic review:
- beforehand outlined search protocol which describes the purpose of the search, key search terms needed, methods and inclusion and exclusion criteria for the systematic review.
- documentation of all actions and decisions that are made during the process, in order to be able to follow, assess and even repeat the used method
- usually, two or more people are needed for implementing a systematic review, especially with screening publications and extracting data
As a result, all publications of different types (including grey literature) that has been written about the research question should be presented and assessed by established standards. A specific tool (e.g. PRISMA) can be used for reporting the process.
The systematic review as a method was first introduced in evidence-based medicine. Because of it’s benefits – transparent and reproducible mechanism and aim to minimize bias by comprehensive coverage – it has been adopted to other fields of science, like social sciences.
Different types of review
- Systematic literature reviews, rapid reviews, umbrella reviews/overview of reviews, scoping reviews, literature reviews/narrative reviews (What are the different types of review? / Covidence)
- Critical review, literature review, mapping review/systematic map, meta-analysis, mixed studies review/mixed methods review, overview, qualitative systematic review/qualitative evidence synthesis, rapid review, scoping review, state-of-art-review, systematic review, systematic search and review, systematized review, umbrella review (A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal)
- Systematic review, rapid evidence assessment, scoping review, integrative review, realist review, narrative review, review of reviews/umbrella review (Reviewing the literature: choosing a review design. Research made simple)
The terminology of review types can vary by discipline and changes over time.
Any review can be done systematically.
Gathering the literature systematically for the review
Systematic reviews take existing literature and synthesize it qualitatively or quantitatively. In order to be systematic and minimize bias, the search must be comprehensive.
- Define the research question
- Choose all the relevant the sources (databases, grey literature, ongoing research)
- Decide the relevant types of literature (articles, books, proceedings, reports etc.)
- Define the relevant publications dates
- Choose the languages
- Formulate search query/queries
- Search (See Search strategy formulation)
- Remove duplicates from the results
- Screen the remaining results
- Set inclusion/exclusion criteria if not already set
- Remember to document your searches so well that you can refer to them in the future and during the rest of the review process. In systematic reviews the searches must be published so that they are reproducible.
Recall and precision
A systematic search aims to find all relevant documents without increasing the search result to unfeasible amounts of references. This means balancing between recall and precision, or sensitivity and specificity. If the precision is increased, also relevant documents may be lost, and the recall will suffer. If the recall is increased, the precision usually suffers. Systematic searching usually means large sets of search results. Understanding the subject thoroughly, defining the research question accurately, and using search techniques correctly save time and effort.
How can library help? The library offers guidance about using databases and constructing search queries as well as basics of some additional tools like Zotero or Covidence.
See the Service policy of guidance.
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