Do you want to know what evidence exists about:
Whether your question relates to policy, industry, practice or research a range of different types of evidence synthesis are available and these are described below. All of the evidence syntheses use the same methodology to systematically search for published and unpublished literature and filter it to identify relevant evidence. However, they differ in terms of the motivation of the review, time and finances available, comprehensiveness of the search and conclusions drawn.
Types of synthesis:
Systematic review (SR) focuses on a specific question and aims to answer it. For example, a SR may be used to estimate the efficacy of an intervention or impact of an exposure. SR uses standardised, systematic methodology to search for evidence (published and unpublished literature from multiple sources) and collate, critically appraise and synthesise it to answer the review question. This methodology aims to be transparent and reduce bias. Studies included may be presented in a searchable systematic map database. Implications for research, policy and practice are provided. View an example of a SR carried out by the CEBA. Guidelines for SR can be found on the Collaboration for Environmental Evidence website.
Systematic mapping (SM) is used to describe the state of knowledge on a focussed or broad topic/question. SM follows the same methodology for systematic review to gather and collate evidence (published and unpublished literature from multiple sources). However, as SM do not set out to answer a question the evidence is not synthesised. One of the key outputs of a SM is a searchable database of included studies and their meta-data (information describing the study and its methods), study location and availability. This database is used to create a narrative report to describe the evidence base, highlight areas of sufficient evidence (evidence clusters) to permit secondary research (eg. systematic review) and subjects not frequently studied (knowledge gaps) that would benefit from primary research. Implications for research, policy and practice are provided. View an example of a systematic map conducted by the CEBA. Guidelines for systematic mapping can be found on the Collaboration for Environmental Evidence website.
Conservation synopses collate multiple sources of evidence for a broad question. A list of actions that conservationists may employ for a particular species group, habitat or conservation issue is drawn up using an advisory board of experts. These actions are organised into categories based on the International Union for the Conservation of Nature (IUCN) classifications of direct threats and conservation actions. In some cases recognised systematic searching methodology is used to collate evidence relating to the actions eg. systematic mapping but this is not always the case. Synopses only include studies that have quantitatively monitored the effect of an action. They describe existing evidence in summary paragraphs but do not make any recommendations on which action to take. View an example of a conservation synopsis that used systematic mapping. For more information about conservation synopses please go to the Conservation Evidence website.
Rapid Evidence Assessment (REA) is a type of evidence review used by the Civil Service. REA follow methodology similar to that used in systematic review but make concessions to the breadth or depth of the systematic review process and are therefore potentially less rigorous. REA provide an informed conclusion on the volume and characteristics of an evidence base, a critical appraisal and formal weighting of that evidence and a synthesis of what the evidence indicates. They include a systematic map database of the studies included. View an example of a REA conducted by the CEBA. An approach to the production of a REA can be found on the Joint Water Evidence Group website.
Quick Scoping Review (QSR) is a type of evidence synthesis used by the Civil Service. QSR aim to provide an informed conclusion of the volume and charachteristics of research evidence relevant to a question or issue, together with a summary of what that evidence indicates. QSR uses similar methodology to systematic review to gather and collate published and unpublished literature but key sources of evidence are identified through limited searches. Evidence is collated and summarised to systematically map the type of evidence available. View an example of a QSR conducted by the CEBA. An approach to the production of a QSR can be found on the Joint Water Evidence Group website.
Overview of different types of evidence synthesis:
|Systematic Review||Systematic Mapping||Conservation Synopses||Rapid Evidence Assessment||Quick Scoping Review|
|7-72 months||6-12 months||12-120 months||5-8 months||3-5 months|
|Motivation||Critical assessment and synthesis of research studies to answer a specific question.||To describe the state of knowledge on a focussed or broad topic/question.||Evidence relating to actions that a conservationists may employ for a particular species group, habitat or conservation issue.||Rapid overview of existing research and synthesis of evidence for a topic/question.||Quick overview of research relating to a topic/question.|
|Uses systematic searching and collation||Yes||Yes||Maybe||Yes||Yes|
|Input from external experts||Yes||Yes||Yes||Yes||Maybe|
|Systematic map database of studies||Maybe||Yes||No||Yes||Yes|
|Critical appraisal of study quality and relevancy and outcomes||Yes||Maybe||No||Yes||No|
|Qualitative and quantitative synthesis of findings||Yes||No||No||No||No|
|Implications for policy, research, practice||Yes||Yes||No||Yes||Yes|