Completing the Forecast Characterizing and Communicating Uncertainty for Better Decisions Using Weather and Climate Forecasts (2006) / Chapter Skim
Currently Skimming:
2 Uncertainty in Decision Making
2 Uncertainty in Decision Making
Pages 15-38
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 15... ...
Following the design of specific forecast products. Instead, and given a general overview of user types and needs for uncertainty that the need for probabilistic forecast products will grow, information, Sections 2.2 and 2.3 summarize, respectively, the committee recommends a process by which NWS can how two streams of research have addressed the question of develop an effective system of provider-user interactions how decision makers interpret and use uncertain informa- that will lead to the design and testing of effective forecast tion -- one from a descriptive perspective (how decisions formats.
|
From page 16... ...
Do we order mandatory evacuations? 1 The decisions made with logical forecasts are informal and intuitive or formal and analytic, forecast producers need to be cognizant of how hydrometeorological forecasts are so numerous and variable forecast information gets used to decide on how to optimally that this report cannot identify and specify the information present its uncertainty.
|
From page 17... ...
In the long term, and more important to hit the right emotional tone and level providing information that is scientifically indefensible will of the message conveyed by the forecast.3 not benefit users' decisions and thus will not satisfy their Much can be learned about users' needs for forecast wants and needs. uncertainty information from the experience of the private The provision of more information is also not always meteorological sector.4 For example, according to one major desirable because additional information can delay or comprivate weather forecasting company, although its clients plicate action, with great costs in situations of time pressure differ widely in their uses of forecasts, there are common and high stakes, especially when information besides hydro meteorological forecast information plays an important role. themes in their needs for uncertainty information.
|
From page 18... ...
to minimize losses. Although the hurricane track forecasts were provided with uncertainty information (e.g., the cone of uncertainty)
|
From page 19... ...
For example, many road weather decisions are primarily driven by budgets.8 Some transportation agencies products to communicate forecast uncertainty (and deciding where to expend resources in doing so) , it is necessary to also prefer a deterministic rather than probabilistic forecast consider user needs and capabilities rather than simply pro- because the weather of interest has such severe consequences viding a large amount of information and expecting it to be that they will treat the roads in the event of any chance of pre cipitation (and would also prefer not to have field staff, aided produce uncertainty information for users, in and of itself, is valuable and 8Presentation indeed critical for creating forecast products tailored for a specific use.
|
From page 20... ...
Probabilistic forecasts of monthly and seasonal rainfall would be needed to generate probabilistic inflow forecasts to assess reservoir refill probabilities by the end of the wet season. The consequences of excess advanced release could be the inability to fill the reservoir by the end of the wet season and, consequently, an inability to meet future energy and water demands.
|
From page 21... ...
Section 2.2.2 describes three complicadramatically, and different types of efforts (e.g., modification tions in the communication of uncertainty information that of an existing decision-support system, or a detailed analysis lie at the root of possible user misinterpretations or rejections of factors that determine decisions and the "safe" introduc- of probabilistic forecasts and point the way to user needs. tion of probabilistic information into that process)
|
From page 22... ...
The ability to combine the personal experiences (e.g., worry or dread) to investment opportunities are just as of many into statistical summaries or to derive forecasts important as statistical variables (e.g., outcomes and their of probabilities from theoretical or statistical models is probabilities)
|
From page 23... ...
Instead people typically decide information is processed by the analytic system, whose out- based on past personal experience. Research has shown that put tends to have less weight in actions or decisions, unless the weight given to small-probability events differs dramatidecision makers have been trained to pay conscious attention cally between the two processing systems (with much greater to statistical information and its implications.
|
From page 24... ...
Most would prefer to take users are to correctly understand and utilize probabilistic their chances at a 50/50 gamble of losing $200 or nothing, forecast products that are typically designed for processing rather than being certain of losing $100. Risk seeking is a by the analytic processing system.
|
From page 25... ...
Many forecast products have the ing the uncertainty of an event is by providing a probability potential to either promote opportunity or to prevent loss estimate of its occurrence, as for example the PoP forecast. or calamity.
|
From page 26... ...
, it seems to Verbal Descriptor From To be a more effective communication format because it allows Very High Confidence 0.5 1.00 people to connect probabilistic information to their personal High Confidence 0. 0.5 Medium Confidence 0.33 0. experience base, where information is typically stored in the Low Confidence 0.05 0.33 form of event counts. In addition, use of relative frequencies Very Low Confidence 0.00 0.05 can help clarify the nature of the target event and reduce the possibility of misunderstanding it.
|
From page 27... ...
. A more recent discovery is the fact to forecast uncertainty may not apply to all forecasts, the that people and organizations are also ambiguity-averse distinction is important both for general users of uncertainty (Ellsberg, 11)
|
From page 28... ...
decision theory is that the key elements that characterize the decision problem can be and have been identified. This entails the identification of 2.3.1 Historical Context • the decision maker's objectives, formalized by a There is a long history of the use of concepts from statistical decision theory12 for the management of risk in numerical utility function that measures preferences with the agriculture, water, energy, insurance, emergency plan- respect to different consequences; • all actions available to the decision maker; ning, and business communities.
|
From page 29... ...
. 2.3.3 Statistical Decision Theory in Decision Support Systems: Findings on Uses in Relation to 13This is the hypothesis that the utility of an agent facing uncertainty is Hydrometeorological Forecasts calculated by considering utility in each possible state and constructing a weighted average.
|
From page 30... ...
In public meetings organized by NWS to publicize its forecast products, the retailer asks for temperature forecasts with higher temperature resolution (i.e., more categories, or a fitted probability distribution)
|
From page 31... ...
If the utility function is nonlinear, the expected utility from forecast A will not equal the expected utility from forecast B even though the published tercile forecasts are the same (i.e., the uncertainty information as to the probabilities matters)
|
From page 32... ...
2.3.3.1 A Formal, Analytic Approach Such as and are readily updated and a key building block that will Statistical Decision Theory Has Value underpin the systematic use of probabilistic hydrometeorological forecasts. This section lists eight findings14 on areas Section 2.2 established that many cognitive and emotional that could profit from further development of such systems factors are involved in decisions and many decisions do and provide NWS with a framework to identify opportuni not reflect the "rational" outcome of utility maximization.
|
From page 33... ...
Similarly, event or weather predic and time, would be beneficial for the development of tions require both monitoring and forecast information to decision-support systems that can use probabilistic forecasts be effectively communicated for risk characterization and and readily demonstrate economic and social value from such mitigation. Finally, consistency in forecasts across multiple use.
|
From page 34... ...
. The specialized users most likely to adopt decisionsupport frameworks, and the intermediaries that work with In addition to developing a greater understanding of the them, are likely to require more detailed information than is relative importance of these factors in limiting the use of probcurrently provided by NWS hydrometeorological forecast abilistic hydrometeorological forecasts in decision-support products -- both in terms of spatial and temporal detail and systems, the Enterprise will be better positioned to generate in terms of the resolution of the probability distributions and communicate uncertainty information that meets users' and their uncertainty.
|
From page 35... ...
their cone of uncertainty format of hurricane track forecasts Nonetheless, most environmental risk management problems in the aftermath of Hurricane Charley. It requested public are inherently multiscale (both temporally and spatially)
|
From page 36... ...
The potential availability of a wide range 2.4.2 One Size Does Not Fit All of different forecast information helps to ensure that the best The population of NWS forecast product users is diverse. information for a particular user group is available.
|
From page 37... ...
Although it may be social, and institutional contexts of the recipient. What to possible to outsource many of these tasks and/or to commisinclude and not include should in part be a function of the sion the research18 and testing of products necessary for the intended user and their ability to handle different sorts design of successful probabilistic forecast products, it may be of information.
|
From page 38... ...
This complexity makes it clear that NWS will help NWS address users' needs for uncertainty informacannot provide a single forecast product that would satisfy tion into the future as users' needs, forecasting capabilities, all users. Instead, the committee recommends designing and technologies evolve.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.