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Decision analysis is a systematic approach to
uncertainties in decision-making, using models
to project outcomes of alternative actions. These outcomes (or "performance
measures") act as criteria for comparing and ranking the actions.
Many possible outcomes are generated for each action, each resulting
from a unique combination of alternative hypotheses about uncertain
states of nature (e.g., historical data usually suggest a range
of ecological responses to management actions; there is always a
range of future possible climate regimes). Such an approach has
several benefits over approaches in which uncertainties are ignored
or treated in an ad hoc manner (e.g., using point estimates for
uncertain parameters).
First, this approach can lead to more risk-averse
management decisions in the long run because it allows decision-makers
to select "robust" actions that perform well under a broad
range of assumptions. Implementing actions that are robust to uncertainties
minimizes risks that the selected action will not have its intended
effect, because such actions have a much higher chance of producing
a favourable outcome even if the underlying hypotheses turn out
to be wrong.
Second, including uncertainties allows risk-averse
actions to be identified and implemented before these uncertainties
are fully resolved. This avoids the common situation where uncertainty
in the predicted effects of management actions discourages decision-makers
from changing management policies from the status quo (Peterman
and Anderson 1999). Avoiding such inaction is particularly important
for situations in which management actions must be taken long before
uncertainties can be resolved to the satisfaction of decision-makers.
Third, explicitly incorporating alternative hypotheses
about key uncertainties supports collaborative processes involving
scientists and agencies with alternative interpretations of existing
data.
ESSA has used decision analysis procedures since
1995 to facilitate stakeholder agreement
on management actions, to help scientists agree on which uncertainties
most critically affect decisions, and to assess the benefits and
costs of adaptive management actions.
References:
 Peterman,
R. and J. Anderson. 1999. Decision analysis: a method for taking
uncertainties into account in risk-based decision making. Human
and Ecological Risk Assessment 5: 231-244.
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