Research synthesis or evidence synthesis is the process of combining the results of multiple
primary research
Research is creative and systematic work undertaken to increase the stock of knowledge. It involves the collection, organization, and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness to ...
studies aimed at testing the same conceptual
hypothesis
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess o ...
. It may be applied to either
quantitative
Quantitative may refer to:
* Quantitative research, scientific investigation of quantitative properties
* Quantitative analysis (disambiguation)
* Quantitative verse, a metrical system in poetry
* Statistics, also known as quantitative analysis
...
or
qualitative research
Qualitative research is a type of research that aims to gather and analyse non-numerical (descriptive) data in order to gain an understanding of individuals' social reality, including understanding their attitudes, beliefs, and motivation. This ...
.
Its general goals are to make the findings from multiple different studies more generalizable and applicable.
It aims to generate new knowledge by combining and comparing the results of multiple studies on a given topic.
One approach is to use a
systematic review
A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from published studies on ...
methods. Communities of practice have developed promoting use of robust evidence synthesis in medicine and social/natural sciences.
Techniques
Meta-analysis
Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...
is the preferred technique of quantitative research synthesis in many fields, such as the social sciences,
medical science
Medicine is the science and practice of caring for patients, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pra ...
and increasingly environmental science. There have also been calls for its use as a generic method to inform decisions It is a statistical technique that combines measures of
effect size
In statistics, an effect size is a value measuring the strength of the relationship between two variables in a population, or a sample-based estimate of that quantity. It can refer to the value of a statistic calculated from a sample of data, the ...
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 impacted by differences between the studies in study design, the type of evidence, or other key characteristics.
For these reasons robust synthesis always includes a strength of evidence assessment.
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.
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.
References
External links
About Evidence SynthesisEvidence Synthesis - What is it and why do we need it? Cochrane
Research methods
{{Sci-stub