Dear D. Burch
Excellent question. The Department of Defense follows Federal Acquisition Regulations, its own directives and other legislative direction as it applies in order to establish a fair competitive environment. Those rules attempt to create objective criteria, by which each competitor can strive to use engineering and formula driven techniques to arrive at the optimum solution when proposing that the government select their product to meet its needs as expressed in a request for proposal.
Unfortunately, because the weapon systems our military needs require the highest technology, there will always be a certain amount of risk associated with almost any major acquisition system being developed to be superior on the battlefield. During the Source Selection process, a government team of the most experienced engineers, cost and accounting specialists, science and technology experts, contract managers, operational users and program managers do their best to assess the likely delays in the proposals, from each competitor, to meet the planned cost, schedule and performance goals.
These assessments are based on the maturity of the technology being used, the documented past performance of each competitor on similar programs and the experience and depth of the management team each competitor will use to develop, test and field the new weapon system. These assessments review objective data, but in the end, the final scores often involve some subjectivity.
So, although we can use very objective scores with regard to fuel burn rates, range, payload, survivability, weapon accuracy and estimated maintenance and sustainment costs, assessing risk that a competitor can deliver as promised on schedule, on cost and meeting all operational requirements is subjective.