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Systematic searching: Start here

Welcome to study systematic searching

This guide provides guidance on the different stages of systematic searching. It focuses on undertaking systematic searches in the 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 varied. Systematic searching also involves careful documentation of the search to ensure it can be reproduced.

Sensitivity and specificity

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. 

A variety of reviews

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 Andor, by searching e.g."literature review" OR "systematic review"

Typology of reviews

A systematic review takes a systematic approach at different stages of the review. 

  • It seeks to answer a well-defined research question
  • the search is carried out systematically and reported accurately
  • Inclusion and exclusion criteria are defined before the start of the review.
  • methodological quality of the selected studies and the risk of bias are carefully assessed

Other types of systematic reviews include:

  • umbrella review
  • integrative review
  • systematized review


Narrative reviews (or literature reviews) characteristically

  • Are methodologically the lightest forms of literature review
  • Describe previous research on the topic
  • Often addresses a broad research question 
  • Literature search is not carried out in a fully systematic way
  • Selective collection of data may result in divergent descriptions of the topic

Sub-types include:

  • critical review
  • scoping review
  • mapping review
  • overview

Some of the sub-types contain features of a systematic review.


A meta-analysis can be qualitative or quantitative.

  • In a qualitative meta-analysis, data are classified and summarised. Qualitative meta-analysis can be divided into meta-synthesis and meta-summary.
    Quantitative meta-analysis involves combining and generalising quantitative studies using statistical methods. The results can be given in numerical form.


Rights of use

Creative Commons -lisenssi
This work is licensed under a Creative Commons Attribution 4.0 International License.

This guide is a translation of the Systemaattinen tiedonhaku llibguide, which is based by a similar guide by the University of Oulu.  Team: Päivi Lukin, Sari Mäkelä, Taina Peltonen, Jaana Isojärvi. The DeepL translator was used in the translation process.

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Steps in a systematic review

1. Framing questions for a review

2. Identifying relevant studies

3. Assessing the quality of studies

4.Summarizing the evidence

5. Interpreting the finding

Reference: Khan KS, Kunz R, Kleijnen J, Antes G. Five steps to conducting a systematic review. J R Soc Med. 2003 Mar;96(3):118-21. doi: 10.1258/jrsm.96.3.118. 


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