most dangerous ones are the many seemingly trivial enhancements that can nibble you to death. If you do not have the knowledge, skill, and discipline to analyze the impact of every small change, the scope of the job can quickly double or triple. The PSP process will help you to control this change spiral. It enables you to make accurate plans and to estimate the probable impact of even the smallest change. These plans provide you, your teammates, and your managers with a rational basis for deciding when to freeze and build and when to make further changes