Therefore, it is worthwhile to invest in any tools that can make error detection occur earlier - from the design documents themselves, for example. This also suggests that the product should be critically reviewed regularly in order to try to find errors earlier, and that programming languages and tools that detect and flag errors earlier are better than more highly flexible systems that fail to detect errors until run time. The models show that the overall project cost increases rapidly when one attempts to accelerate a project to finish ahead of schedule. This is not a surprise. Here at last is hard data to support a manager who wants to honestly refuse to commit delivery of a product at an unreasonably early date.
People are fairly accurate at estimating how far ahead of schedule they are.
They are not so good at estimating how far behind schedule they are. Estimates by experienced managers of the actual time to completion of a project tend to be somewhat optimistic. Plotting the estimated time to completion against the actual time to completion and fitting a line to the data led Boehm to the conclusion that managers tend to be optimistic when they are behind schedule. The task during that time is to trace how the cost driver factors change as new technology is brought to bear on the software development enterprise.