Introduction
Methods
Results
Time constraints
Financial resource constraints
Controversy caused by conflicts of evidence
Controversy caused by conflicts of values and/or interests
Serious and/or unacceptable consequences of making the wrong decision
Diversity of knowledge and information
High uncertainty
Synthesis method | Overview | Specific needs, resource requirements and limitations | Key advantages and suitability |
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Expert consultation | A range of experts is asked to provide their knowledge and/or opinion on the question, possibly supporting it with selected published literature. This can be done in meetings or by individual consultation | Available expertise at short notice over a few days, restricted use in conflict situations with contested knowledge claims and risk of advocacy science (see Ehrmann and Stinson 1999). Process susceptible to biased/random selection of experts | Relatively quick and inexpensive approach for well-defined, uncontested policy problems |
Expert elicitation/consultation with Delphi process | In the Delphi method, a coordination team or a facilitator designs a questionnaire which is sent to a group of experts. The expert evaluations are then summarized by the coordination team and the summary is sent to the respondents who are given the opportunity to reconsider their original answers in the light of the responses by others. The assumption is that the expert opinions gradually converge as the experts consider the various aspects of the problem and learn from one another. The process is stopped after having completed a pre-defined number of rounds, or reaching a sufficient level of consensus. The mean or median scores of the final rounds are used a result of the process (Linstone and Turoff 2002). Divergent opinions, should they persist are usually made explicit | There are different types of Delphi method based inquiries. Policy Delphi is designed to explore a pressing policy issue and support subsequent decision making. Structural Model Delphi aims for exploring causal relationship and building a systems understanding or model. Trend Model Delphi is designed to initiate discussion on trends and potential future development. Can take longer than expert consultation therefore resources required are greater | Compared to expert consultation, a slightly more systematic and rigorous approach, which usually makes the process of reaching a result more transparent as well as recording divergent opinions and their reasoning. Several rounds usually lead to a more thorough reflection of different issues and perspectives than a single meeting or separate interviews (Mukherjee et al. 2015) |
Causal chain analysis (CCA) & Bayesian belief networks (BBN) | CCA establishes relationships between different factors by flow diagrams depicting causal linkages. Often conducted jointly with experts and other stakeholders. Can serve as a first step to more elaborate modelling approaches and/or reviews of evidence on the different causal links identified, e.g. systematic reviews. Bayesian belief models are a specific derivation of CCA technique to try and estimate probabilities and how they multiply throughout the causal chain. The key feature of BBNs is that they enable us to model and reason about uncertainty. The BBN forces the assessor to expose all assumptions about the impact of different forms of evidence and hence provides a visible and auditable dependability or safety argument (for details see Fenton and Neil 2012) | Relies entirely on the expertise of the participants involved, can provide a structured overview of issues involving a broad range of different factors in relatively short time spans, does not per se provide evidence and usually does not adequately capture complex interactions | Can be used to reach agreement on the different issues and factors involved and thus help to frame or scope a problem, particularly if different types of knowledge including experiential and highly context-specific and/or place- based knowledge is relevant. Usually needs to be combined with other methods to provide an overview of the knowledge acquired on the different causal links (Uusitalo 2007) |
Systematic review (SR) | Highly structured and standardised protocol-driven process for synthesising evidence; methods specified a priori; can minimise bias and optimise precision of quantitative outcomes; different approaches used for quantitative or qualitative synthesis. Always includes an extensive search for all relevant evidence and critical appraisal of the included evidence; may quantitatively combine evidence to improve precision (Gough et al. 2012; CEE 2013) | Requires a focused question that can be clearly specified as a set of specific inclusion criteria and sufficient evidence (studies) that address these criteria. Team activity. Based on an a priori peer-reviewed protocol. As such, usually takes months rather than days or weeks to complete | Well-regarded as robust method for synthesising evidence on specific outcomes, so standard methods are available. Defensible approach for contentious topics. Could potentially: Increase precision Minimise bias Ensure transparency Facilitate stakeholder involvement (e.g. in a-priori protocol development) Clarify uncertainty A major advantage is the possibility to up-date the review without repeating the whole process Suitable for independent measurement of effectiveness of an intervention when there is dispute among stakeholders, sufficient quantitative evidence and sufficient time (months) to complete the review. See http://www.environmentalevidence.org/completed-reviews
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Systematic map (SM) | Highly structured and standardised protocol-driven process for mapping evidence similar to SR with extensive search but differing primarily in being able to answer a broader question than SR, and not aiming to quantitatively combine evidence; may not include extensive critical appraisal; useful for summarising state of the art for a particular question, possibly to identify or prioritise questions for later SR (Gough et al. 2012; CEE 2013) | Can answer specific or broad questions so long as the question is structured well enough to enable the setting of practical inclusion criteria. Team activity. Based on an a priori peer-reviewed protocol. As such, usually takes months rather than days or weeks to complete. Main limitations are that outcomes are synthesised in less detail than in SR, often as a classification, and may not be appraised critically | Possibly more flexible than SR as could accommodate a broader question and cover a relatively wide range of outcomes, albeit with less detail and rigour. Provides a systematic (defensible) way of establishing “state of the art”. Could also potentially: Ensure transparency Facilitate stakeholder involvement Provide a basis for more focused question development or prioritisation for future SR A major advantage is the possibility to up-date the map without repeating the whole process Suitable when addressing a question of impact or effectiveness when there are multiple possibilities in subject, intervention/exposure and outcomes such that a full synthesis of all elements of the question would not be feasible. See http://www.environmentalevidence.org/completed-reviews
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Focus groups | Structured discussion of an issue by a group of people, purposively selected usually to involve different stakeholders and/or potentially differing perspectives of an issue at hand. The joint discussion allows participants to consider and react to arguments put forward by other participants so it allows examination of group dynamics and opinion formation (Orvik et al. 2013) | Requires highly skilled facilitation, particularly in situations involving conflicting interests or values. All relevant perspectives should be represented and encouraged to be expressed during discussion | Is useful in situations where evidence is not readily available, different types of knowledge are relevant and/or issues are controversial or where the exact question or knowledge need is not yet clearly identified. Can be combined with other methods, e.g. conducted with a group of experts, or a causal chain analysis can be part of a focus group (Orvik et al. 2013) |
Discourse field analysis (DFA) | Discourse field analysis is a structured method for investigating conflicts and alliances among different knowledge holders or stocks of knowledge when discourses are emerging (“input level”, cf. Ottow 2002). Aim is to identify systematically the key issues and actors, and the latter’s location within a discourse field; distinguishing between certain and uncertain knowledge, and determining which knowledge claims are points of conflict between different groups in society and the sciences is a major perspective. In this regard, the focus is on arguments, procedures or putative facts that are seen as correct or true by the actors under analysis, rather than on which are true. The outcome is a picture of the discourse landscape with all its contradictions. It emphasises the negotiating processes that take place within a discourse field, i.e. DFA differs from a discourse analysis as a method in social sciences that traces the interaction of knowledge and power at the “outcome level” in order to show how power is exercised in a society through discourses, e.g. question of rules, controls or exclusion (Foucault 1971) | Can address highly contested issues in complex situations and includes different types of knowledge (scientific, technical, professional, everyday knowledge). Time and labour needed depends on the complexity of the issue; works best with written resources, but can be enhanced with interviews for acquiring tacit knowledge | Addresses the following questions: Which issues are high on the agenda of public discussion? Who are the central actors who carry out this discussion; what is their position within the discourse; and in which context do they move? Which knowledge claims concerning problematic cause-effect relationships count as certain and which as uncertain? Which societal needs for action can be deduced from the discourse, and which research needs (for both the natural and the social sciences)? Are there new, emergent issues, and who are their protagonists? Can one find examples that show to what practical action (implementation projects) a societal discourse leads? Lux (2010) |
Multi criteria analysis (MCA) | MCA is a methodology for supporting complex decision-making situations with multiple and conflicting objectives that decision-makers and other stakeholder groups value differently. The basic idea of MCA methods is to evaluate the performance of alternative courses of action (e.g. management or policy options) with respect to criteria that capture the key dimensions of the decision-making problem (e.g. ecological, economic and social sustainability), involving human judgment and preferences (Belton and Stewart 2002). MCA methods are rooted in operational research and support for single decision-makers but recently the emphasis has shifted towards multi-stakeholder processes to structure decision alternatives and their consequences, to facilitate dialogue on the relative merits of alternative courses of action, thereby enhancing procedural quality in the decision-making process (Mendoza and Martins 2006) | Usually requires expertise on decision analysis software Possibly limited representativeness (only a small group of stakeholders usually involved) Some criteria such as cultural heritage or provisioning services vital for sustenance might not be amenable for trade-offs (though some MCA methods can also address these so-called lexicographic preferences) Allows manipulation if not used in a participatory and transparent way | Feasible to address trade-off situations with multiple decision making criteria. Suited for knowledge synthesis processes characterized by incomplete information because they allow a mixed set of both quantitative and qualitative data, including scientific and local knowledge Can combine information about the impacts of alternative courses of action with information about the relative importance of evaluation criteria for different stakeholders. Deliberative-analytic methodology which can support participatory processes and transparent decision making. |
Joint fact finding (JFF) and double sided critique (DSC) | JFF is an emerging strategy for experts, decision makers and key stakeholders from opposing sides of an issue to work together to resolve or narrow factual disputes over public policy issues, including environmental issues. In JFF, the participants jointly determine the questions to be addressed and the best process for gathering information, and they also review the preliminary results of the process, including policy implications, before the results are presented to decision makers (Ehrmann and Stinson 1999) DSC is a similar approach that allows dual description beyond naturalization or culturalization. Thus, the opposing sides highlight the shortcomings of the other argumentation and methodological approach in order to better identify where disagreement lies and with which approaches it could be addressed (Bateson 2002; Bergmann et al. 2012) | The dialogue is usually assisted by a professional facilitator or mediator. Resources are needed to carry out e.g. reviews or hire experts, in some (rare) cases even carry out new empirical research. JFF processes are often lengthy, depending of the needs to summarise evidence, and they require commitment and sustained involvement from the participants | Suitable for building common ground in highly contentious issues, promoting reflective policy learning, and even resolving persistent disputes (Innes and Connick 1999) |
Policy context | Seeking greater understanding or predictive power | Scenario building | Horizon scanning | Seeking understanding of changes in time and space | Seeking measures of anthropogenic impact |
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Time constraints—short policy window | Expert consultation, causal chain analysis | Expert consultation | Expert consultation | Expert consultation | Expert consultation, causal chain analysis |
Financial resource constraints | Expert consultation, causal chain analysis | Expert consultation | Expert consultation | Expert consultation | Expert consultation, causal chain analysis |
Controversy/conflicts of evidence | Systematic review/map, joint fact finding | N/A | Expert consultation—Delphi process | Systematic review, Delphi process | Systematic review, joint fact finding |
Controversy/conflicts of values or interest | Focus groups, systematic review/map | N/A | Expert consultation—Delphi process | Systematic review, joint fact finding | Focus groups, systematic review |
Serious or unacceptable consequences of making the wrong decision | Systematic review | N/A | Expert consultation—Delphi process | Systematic review | Systematic review |
Diversity of knowledge/information | Focus groups, joint fact finding | N/A | Expert consultation—Delphi process | Systematic map, joint fact finding | Focus groups, systematic map |
High levels of uncertainties | Expert consultation, causal chain analysis, Bayesian belief network | N/A | Expert consultation—Delphi process | Systematic review | Systematic review, expert consultation, causal chain analysis, Bayesian belief network |
Policy context | Seeking measures of effectiveness of interventions | Seeking appropriate methodologies | Seeking optimal management | Public opinion and/or perception | Seeking peoples’ understanding of an issue |
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Time constraints—short policy window | Expert consultation, causal chain analysis | Expert consultation | Expert consultation | Expert consultation | Expert consultation |
Financial resource constraints | Expert consultation, causal chain analysis | Expert consultation | Expert consultation | Expert consultation | Expert consultation |
Controversy/conflicts of evidence | Systematic review, joint fact finding | Systematic review/map, joint fact finding | Systematic review, multi-criteria analysis | Systematic review, discourse field analysis | Systematic review, discourse field analysis |
Controversy/conflicts of values or interest | Focus groups, systematic review | Focus groups, systematic review, double-sided critique | Systematic review, multi-criteria analysis | Systematic review, discourse field analysis | Systematic review, discourse field analysis |
Serious or unacceptable consequences of making the wrong decision | Systematic review | Systematic review | Systematic review | Systematic review, discourse field analysis | Systematic review, discourse field analysis |
Diversity of knowledge/information | Focus groups, Systematic map | Systematic map, double-sided critique | Systematic map | N/A | N/A |
High levels of uncertainties | Systematic review, expert consultation, causal chain analysis, Bayesian belief network | Expert consultation, Bayesian belief network, systematic review | Systematic review | N/A | N/A |