does not necessarily mean failure. For example, problems that consist of several phases may require several passes through the sequence, so that each phase can incorporate feedback from earlier phases.
The five-step methodology matches closely with the rational decision-making model studied by economists and political scientists, an approach that was discredited as a descriptive model for organizations and economics by March and Simon (1958) and for political decision making by Allison (1971). In systems engineering, however, the methodology is intended to be normative rather than descriptive. Moreover, the systems engineering context lacks the computational and organizational limitations that social scientists highlighted for practical economic and political situations.
Recent work has focused on extending the basic approach. Many situations, especially large defense projects, require consideration of legal and contractual issues in addition to technological evaluation (Blanchard, 1998, and DOD, 1996). The nature of complexity and the search for general approaches to describing it have altered some features of the basic approach (Albin and Foley, 1998). Several researchers have developed and employed ''soft" methodologies for working with problems that have loose, ill-structured, or ill-defined specifications (Checkland and Scholes, 1990). The methodology described in the body of this report relies primarily on the basic methodology without these recent additions, but extensions could be accommodated easily.
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