Reproduced from: Bettany-Saltikov, J. (2010). Learning how to undertake a systematic review: Part 1. Nursing Standard, 24(40): 47-55.
|Systematic Review||Literature Review|
|Question||Focused on a single question||Not necessarily focused on a single question, but may describe an overview|
|Protocol||A peer review protocol or plan is included||No protocol is included|
|Background||Both provide summaries of the available literature on a topic|
|Objectives||Clear objectives are identified||Objectives may or may not be identified|
|Inclusion and Exclusion Criteria||Criteria stated before the review is conducted||Criteria not specified|
|Search Strategy||Comprehensive search conducted in a systematic way||Strategy not explicitly stated|
|Process of Selecting Articles||Usually clear and explicit||Not described in a literature review|
|Process of Evaluating Articles||Comprehensive evaluation of study quality||Evaluation of study quality may or may not be included|
|Process of Extracting Relevant Information||Usually clear and specific||Not clear or explicit|
|Results and Data Synthesis||Clear summaries of studies based on high quality evidence||Summary based on studies where the quality of the articles may not be specified. May also be influenced by the reviewer's theories, needs and beliefs|
|Discussion||Written by an expert or group of experts with a detailed and well grounded knowledge of the issues|
A meta-analysis goes beyond critique and integration and conducts secondary statistical analyses on the outcomes of similar studies. It is a systematic review that uses quantitative methods to synthesize and summarize the results.
An advantage of a meta-analysis is the ability to be completely objective in evaluating research findings. Not all topics, however, have sufficient research evidence to allow a meta-analysis to be conducted. In that case, an integrative review is an appropriate strategy.
A meta-analysis may be part of a systematic review.
What is a meta-synthesis?
First of all, what is a meta-synthesis? According to Screiber et al. (1997, p.314), a meta-synthesis “is bringing together and breaking down of findings, examining them, discovering essential features and, in some way , combining phenomena into a transformed whole” In basic terms, a meta-synthesis is the ‘bringing together’ of Qualitative data to form a new interpretation of the research field.
Meta-synthesis Vs. Meta-analysis: Whats the difference?
Unlike a meta-analysis which is used to aggregate findings to establish ‘truths’, for example, if an intervention has a true effect on a variable, a meta-synthesis can lead to new interpretations of research. This can result in new theories being developed.
In summary, a meta-analysis is a way of testing a hypothesis whereas a meta-synthesis is a way of developing a new theory.
Three main types of Meta-synthesis
1) Theory Building – This form of meta-synthesis brings together findings on a theoretical level to build a tentative theory.
2) Theory Explication – This form of meta-synthesis is a way of reconceptualising the original phenomenon.
3) Descriptive – This form of meta-synthesis provides a broad description of the research phenomenon.
These forms of meta-synthesis are not discrete, they are complementary. The aim of Meta-synthesis usually overlap as you will see in the example later on.
Why use a meta-synthesis?
Qualitative data is useful for providing a snapshot at one person’s interpretation of an event or phenomenon. By bringing together many different interpretations you are strengthening the evidence for an interpretation by discovering common themes and differences & building new interpretations of the topic of interest.
A literature review is something most of you have done this at one time or another. As a publication type it is an article or book published after examination of previously published material on a subject. It may be comprehensive to various degrees and the time range of material scrutinized may be broad or narrow, but the reviews most often desired are reviews of the current literature. The textual material examined may be equally broad and can encompass, in medicine specifically, clinical material as well as experimental research or case reports. State-of-the-art reviews tend to address more current matters. A review of the literature must be differentiated from HISTORICAL ARTICLE on the same subject, but a review of historical literature is also within the scope of this publication type. The literature review examines published materials which provide an examination of recent or current literature. Review articles can cover a wide range of subject matter at various levels of completeness and comprehensiveness based on analyses of literature that may include research findings. The review may reflect the state of the art. It also includes reviews as a literary form.
An integrative review summarizes past research and draws overall conclusions from the body of literature on a particular topic. The body of literature comprises all studies that address related or identical hypotheses. In a properly executed integrative review, the effects of subjectivity are minimized through carefully applied criteria for evaluation. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor and replication.
At its most basic, narrative reviews are most useful for obtaining a broad perspective on a topic and are often more comparable to a textbook chapter including sections on the physiology and/or epidemiology of a topic.
When reading and evaluating a narrative review, keep in mind that author's bias may or may not be present. The labels Narrative Review and Literature Review are often describing the same type of review.
For scientific purposes, the term Literature Review is the one used most often.