• Page 4, Line 31: Not sure this is entirely true in the case of this example. Please further elucidate the concepts of aleatory and epistemic. Consider using more accessible terms for the concepts.

  • Page 4, Line 33: Replace “inherently” with “often.”

  • Page 5, Line 1: Is it not true that probabilities can only be assigned on empirical quantities.

  • Page 5, lines 19-20: The terms “parametric analysis” and “switchover” could be made more accessible by using the phrase “sensitivity analysis,” which is used commonly in the climate research community.

The Importance of Quantifying Uncertainty

The committee suggests that the content of this chapter be merged with that of Chapter 6 under the rubric of communication and that this material be placed near the current location of Chapter 6 (after the discussion of the sources and types of uncertainty and the various methods for characterizing uncertainty). It would also be helpful if the authors provided some background information on the research process that led to the formulation of the terminology for numerical probabilities outlined in the figures and tables. This chapter could also be an appropriate place for further elaborating on the concept of risk, wherein probabilities are combined with consequences.

Cognitive Challenges in Estimating Uncertainty

In this chapter the authors provide an excellent summary of the cognitive challenges that affect rational analysis of uncertainty by individuals. We normally consider decisions to be made cognitively, and the ideal decision is made “rationally,” with a calculus of plusses and minuses, tradeoffs, and net gain or loss. This leads to an emphasis on cognitive elements in judgments and decisions and a relative under-emphasis on other factors influencing people’s estimates of uncertainty. Two factors that ought to be discussed, at least briefly, are group processes of decision making and the role that emotions play.

People are often asked to make decisions about issues that are complex and involve uncertainty in terms of potential outcomes. These decisions are most often made in groups and in institutional settings. The context of decision making presents important constraints and opportunities on the processes and outcomes. One factor is the worldview of the group, for example as analyzed by Mary Douglas, Aaron Wildavsky,

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