About this complex problem Larry Bernstein, Industry Research Professor at Stevens Institute of Technology, writes: "The performance of new systems capabilities for government agencies and industry are often examined using simulators. The simulators provide insight into how the new capabilities will perform. The simulators shed little light on reliability, complexity and other software engineering aspects of the proposed changes. The correlation between the complexities of the proposed capabilities with that of an earlier system can be used to bound the trustworthiness, possible schedule and potential costs for implementing the new capability.

Larry continues, "I call this the "Lambda Protocol." It combines software reliability with software sizing theory. With performance, reliability, schedule and cost-estimates in hand, system and software engineers can make essential engineering tradeoffs as they set a course of action."

Here is Larry's complete article: Taking Software Requirements from Folklore to Analysis.