In the haze of battle surrounding most development efforts, software development models provide the answer. However, as with any other product, there are many dimensions to software quality. Software development models can directly account for many of these quality factors, either directly through estimates, i.e., defects delivered, or via parameter settings that in turn drive estimates. Variables typically include complexity of the software to be developed, specification and test level, quality of the development staff and tools, complexity of the development language, and software size. Vendors of more mature tools have had a longer opportunity to collect data and perform enhancements, so more variables are generally available for their models.
Parametric models have several advantages over other methods of prediction.
First, vendors work continuously to assure that their tools are accurate. The better tools also can be substantially calibrated to the specifics of an organization while retaining the essential sensitivities of key parameters. For the concurrent engineering necessary to simultaneously satisfy cost, schedule, requirements, and quality goals, the benefit of parametrics is clear. No other method permits such rapid, elaborate interaction between varied interests. Once development goals are set, parametric estimates can be used by developers to ensure that quality goals are achieved at least cost.