"Warning sources often seem to assume that there will be immediate reception of the warning, unlimited attention to the warning message, perfect comprehension of message content based upon accurate prior knowledge about the threat, and perfect compliance with the recommended actions. None of these conditions will occur, even though reception, attention, comprehension, and personalization increase when there is an imminent threat. Consequently, warning systems and warning strategies must be carefully designed to make it more likely that warnings will be as effective as possible. The first step in warning system design is to define the desired message effects, especially the behavioral objectives of the system-what actions do authorities want the end-users to take? The second step is to identify any distinctively different segments of the target population-how do people differ in terms of their abilities to receive a warning, attend to it, comprehend its content, personalize the threat, choose an appropriate protective action, and implement that protective action? The third step is to identify the channels through which warning messages will be transmitted-what technologies and what intermediate sources are needed? Finally, warning system designers must define who the initial message sources will be and develop their perceived credibility by taking steps to ensure their expertise and trustworthiness". (Partnership for Public Warning, Protecting America's Communities, 2004, p. 7)