Develop Alternative Solutions and Selection Criteria

Alternatives are based on potential product architectures and span a design space of feasible solutions. The Design Product or Product Component specific practice of the Develop the Design specific goal contains more information about developing potential product architectures to incorporate into alternative solutions for the product.

As selections are made, the design space may be constricted and other alternatives examined until the most promising (i.e., optimal) solutions that meet requirements and criteria are identified. The selection criteria identify the key factors that provide a basis for the selection of the solution. These criteria should provide clear discrimination and an indication of success in arriving at a balanced solution across the life of the product. They typically include measures of cost, schedule, performance, and risk.

The alternative solutions evaluated frequently encompass alternative requirement allocations to different product components. These alternatives may also be structured to evaluate the use of COTS solutions in the product architecture. Processes associated with the Requirements Development process area would then be employed to provide a more complete and robust provisional allocation of requirements to the alternative solutions.

Selection of the best solution establishes the requirements provisionally allocated to that solution as the set of allocated requirements. The circumstances in which it would not be useful to examine alternative solutions are infrequent in new developments. However, developments of precedented product components are candidates for not examining, or only minimally examining, alternative solutions.

• Establish and maintain a process or processes for identifying solution alternatives, selection criteria, and design issues. Selection criteria are influenced by a wide variety of factors driven by the requirements imposed on the project as well as the product life cycle. For example, criteria related to mitigating cost and schedule risks may influence a greater preference for COTS solutions provided such selections do not result in unacceptable risks for the remaining product components to be developed. When using existing items, such as COTS, either with or without modification, criteria dealing with diminishing sources of supply or technological obsolescence should be examined, as well as criteria capturing the benefits of standardization, maintaining relationships with suppliers, and so forth. The criteria used in selections should provide a balanced approach to costs, benefits, and risks.
• Identify alternative groupings of requirements that characterize sets of solution alternatives that span the feasible design space. Effective employment of COTS alternatives can provide special challenges. Knowledgeable designers familiar with candidate COTS alternatives may explore architectural opportunities to exploit potential COTS payoffs.
• Identify design issues for each solution alternative in each set of alternatives.
• Characterize design issues and take appropriate action. Appropriate action could be to characterize the issues as a risk for risk management, adjust the solution alternative to preclude the issues, or reject the solution alternative and replace it with a different alternative.
• Obtain a complete requirements allocation for each alternative.
• Document the rationale for each alternative set of solutions.