• What are opt-out rates and causes? Would more tailored opt-out options reduce the opt-out rate? For example, would allowing people to opt in or out of specific categories or sources of warnings help? If so, is there an optimal level of granularity for such selections? How can people be encouraged to opt back in?

• For a given alerting system, what is the most effective repetition frequency for messages and the most effective update interval during an extended emergency? Does this depend on the nature of the hazard or message?

• How can one determine the effectiveness of the alerts or warnings issued during an event? Can the effectiveness of particular messages or systems be measured directly? If not, are there indirect indications that can be used to gauge effectiveness?

VALUE OF GEOTARGETED INFORMATION

Geotargeted information can be presented in several ways: for example, text that includes a place name (e.g., city, county, or zip code), a map that clearly delineates the affected area, a map that shows the affected area and includes the location of the message recipient, or some combination of these. Open research questions regarding the display and presentation of geotargeted information include the following:

• How would using multiple approaches to communicate geotargeted alerts and warnings enhance personalization of risk and subsequent public protective action response? What combinations of text and maps would best motivate recipients to take protective action?

• Does the content of the message—for example, the hazard being warned about or the protective action being urged—play a role in which presentation method is best?

• Given that targeting and sending messages to recipients in unnecessarily large geographic areas can lead to frustration and opting out, what is the most effective size of geotargeting boundaries?

• If maps are incorporated into alerts, what is the most effective method to represent, transmit, and display them? For example, should the maps be represented as raster or vector images? What image size and resolution are best? What level of compression is needed? Should messages contain the maps themselves or just links (e.g., URLs) to the maps?

• How will map literacy in the general populace affect public response? Will map literacy need to be incorporated into disaster education?

• What are the most effective design and visualization principles for geotargeted alerts? Which map symbols, scales, labels, and point of inter-



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