Cost framework for COTS evaluation

We focus on factors that the user should consider when deciding whether to use COTS software. We take the approach of using the common denominator, cost. This is done for two reasons: first, cost is obviously of interest in making such decisions, and second a single metric (cost in dollars), can be used for evaluating the pros and cons of using COTS. The reason is that various software system attributes, like acquisition cost and availability (i.e., the percentage of scheduled operating time that the system is available for use), are commensurate quantities. That is, quantitatively “a low acquisition availability”. These units are not multiplicative. However, if it were possible to translate availability into either a cost gain or loss for COTS software, we could operate on these metrics mathematically. Naturally, in addition to cost, the user application is key in making the decision. Thus one could develop a matrix where one dimension is application and the other dimension is the various cost elements. We show how cost elements can be identified and how cost comparisons can be made over the life of the software. Obviously, identifying the costs would not be easy. The user would have to do a lot of work to set up the decision matrix but once it was constructed, it would be a significant tool in the evaluation of COTS. Furthermore, even if all the required data cannot be collected, having a framework that defines software system attributes would serve as a user guide for factors to consider when making the decision about whether to use COTS software or in-house developed software