Economic evaluation of testability and diagnosability for commercial off the shelf equipment

Commercial off the shelf (COTS) equipment is generally preferred because of its low acquisition costs, wider user base and implied support from the vendor. Because it is treated as a black box, however, it is often complicated to measure the testability and diagnosability of the COTS equipment and therefore its supportability is difficult to predict. While some metrics for testability, diagnosability and supportability exist, they usually require examination of schematic details - and require design changes to improve these attributes. This is not practical for COTS. The best that a designer of COTS based systems can expect is to evaluate various competing COTS and assess their testability attributes. We propose a set of scoring attributes and a methodology to achieve this goal without the need for schematic level information.