{{Short description|Combination of results from multiple primary studies}} '''Research synthesis''' or '''evidence''' '''synthesis''' is the process of combining the results of multiple primary research studies aimed at testing the same conceptual hypothesis. It may be applied to either quantitative<ref name="handbook">{{Cite book |chapter-url=https://books.google.com/books?id=p-aFAwAAQBAJ |title=The Handbook of Research Synthesis |last1=Hall |first1=Judith A. |last2=Tickle-Degnen |first2=Linda |last3=Rosenthal |first3=Robert |last4=Mosteller |first4=Frederick |date=1993-11-23 |publisher=Russell Sage Foundation |isbn=9781610441377 |editor-last=Cooper |editor-first=Harris |chapter=Hypotheses and Problems in Research Synthesis |author-link3=Robert Rosenthal (psychologist) |author-link4=Frederick Mosteller |editor-last2=Hedges |editor-first2=Larry V. |editor-link2=Larry V. Hedges}}</ref> or qualitative research.<ref name="qrj">{{Cite journal |vauthors=Suri H |date=2011-08-03 |title=Purposeful Sampling in Qualitative Research Synthesis |journal=Qualitative Research Journal |volume=11 |issue=2 |pages=63–75 |doi=10.3316/QRJ1102063 |issn=1443-9883}}</ref> Its general goals are to make the findings from multiple different studies more generalizable and applicable.<ref>{{Cite journal |vauthors=Wyborn C, Louder E, Harrison J, Montambault J, Montana J, Ryan M, Bednarek A, Nesshöver C, Pullin A |date=August 2018 |title=Understanding the Impacts of Research Synthesis |journal=Environmental Science & Policy |volume=86 |pages=72–84 |doi=10.1016/j.envsci.2018.04.013|doi-access=free }}</ref>
It aims to generate new knowledge by combining and comparing the results of multiple studies on a given topic.<ref name="handbook" /> One approach is to use a systematic review method.
==Techniques== Meta-analysis is the preferred technique of quantitative research synthesis in many fields, such as medical science. It is a statistical technique that combines measures of effect size from a number of studies to calculate an overall measure. This measure of effect has greater precision (less uncertainty) than the individual studies, but it may be biased by differences between the studies in study design, the type of evidence, or other key characteristics.<ref name="os"/>
In qualitative research, methods of synthesis include narrative synthesis and meta-ethnography. Narrative synthesis allows researchers to address a wide range of questions in their review, while meta-ethnography aims to preserve the cultural context in which the original findings of the included studies were generated.<ref name="qrj"/><ref name="os">{{Cite journal | vauthors=Denyer D, Tranfield D, van Aken JE |date=March 2008 |title=Developing Design Propositions through Research Synthesis |journal=Organization Studies |volume=29 |issue=3 |pages=393–413 |doi=10.1177/0170840607088020 |s2cid=143261509 |issn=0170-8406}}</ref><ref>{{cite journal | vauthors = Barnett-Page E, Thomas J | title = Methods for the synthesis of qualitative research: a critical review | journal = BMC Medical Research Methodology | volume = 9 | issue = 1 | pages = 59 | date = August 2009 | pmid = 19671152 | pmc = 3224695 | doi = 10.1186/1471-2288-9-59 | doi-access = free }}</ref> The narrative synthesis approach has attracted criticism because of its potential for bias, with critics highlighting the subjective nature of the use of the method to draw conclusions. There is also evidence that reviews using the narrative synthesis approach often suffer from a lack of transparency.<ref>{{cite journal | vauthors = Campbell M, Katikireddi SV, Sowden A, Thomson H | title = Lack of transparency in reporting narrative synthesis of quantitative data: a methodological assessment of systematic reviews | journal = Journal of Clinical Epidemiology | volume = 105 | pages = 1–9 | date = January 2019 | pmid = 30196129 | pmc = 6327109 | doi = 10.1016/j.jclinepi.2018.08.019 }}</ref>
== References == {{Reflist}}
Category:Research methods
== External links ==
* [https://evidencesynthesis.org/about/about-evidence-synthesis/ About Evidence Synthesis] * [https://www.cochrane.org/news/evidence-synthesis-what-it-and-why-do-we-need-it Evidence Synthesis - What is it and why do we need it?], Cochrane {{Sci-stub}}