Reasons for Estimating
There are many reasons for estimating, including:
Many cost and schedule overruns can be traced back to a poorly developed estimate. Even when the overrun is the result of poor execution, a good estimate should have included allowances for this. For example suppose you estimate the project at a low cost by using fewer resources and shorter durations than required, and then the project is authorized and you are the project manager. You find yourself committed to the project with insufficient resources and insufficient time. The probability of completing a successful project is very low. However, if you had done the estimate had been done correctly, it would have included sufficient resources and an appropriate schedule.