This guide provides guidance on the different stages of systematic searching. It focuses on undertaking systematic searches in health sciences and medicine, but the guidelines can be applied to other fields as well.
Systematic searching is usually associated with systematic reviews, but the guidelines can be applied to all types of comprehensive and in-depth searching. Comprehensiveness is achieved by keeping the search terms, search methods and database selection sufficiently versatile. Systematic searching also involves careful documentation of the search to ensure it can be reproduced.
A systematic literature search aims to find all relevant documents on a topic without increasing the search result set to such an extent that it is no longer possible to sift through the search result. The concepts of recall (or sensitivity) and precision (or specificity) are related to information retrieval.
Recall = the ratio of hits in the search result to all relevant documents in the database. The proportion of relevant documents in the database that were found.
Precision = the ratio of hits in the search result to all documents found. What percentage of the search result consisted of relevant documents.
Source: Järvelin K, Sormunen E. Tiedon tallennus ja haku
The relationship between recall and precision is inverse. If you increase the precision, i.e. reduce the number of irrelevant documents in the search result, you may also lose relevant documents, i.e. your recall will suffer. If the recall is increased, i.e. the search becomes more comprehensive, precision may suffer.
Systematic information retrieval is a balancing act between sufficient recall and precision. Systematic searching as a method involves searching through a large set of search results where necessary. Good knowledge of the subject and search techniques, search planning and persistent testing of search phrases will usually lead to the best results in terms of both recall and precision.
The types and names of reviews vary between disciplines, but also within a discipline. Different types of reviews are used for different purposes. Common to the different types of reviews is the search, evaluation, synthesis and analysis of the literature.
Familiarise yourself with the type of review you have chosen. The last tab of this guide contains methodological literature on literature reviews. You can find more on Oula-Finna, by searching e.g. "literature review" OR "systematic review"
A systematic review takes a systematic approach to different stages of the review.
Other types of systematic reviews include:
Narrative reviews (or literature reviews) characteristically
Some of the sub-types contain features of a systematic review.
A meta-analysis can be qualitative or quantitative.