Your manager probably has asked you come up with some estimates. Without well-defined requirements and comparable historical information, project managers often resort to randomly pulling a number from thin air.

Such approach is so problematic because there is no basis for the estimates. Oftentimes, the assumptions are also not documented. Moreover, you will be held accountable for the poor estimates that you provided and you’ll have no way to defend yourself if questions arise.

To avoid this problem, clearly define the scope of the work that you need to estimate. Create a mini-WBS as appropriate. Look for comparable work from which you can derive educated estimates and make sure to document all of your assumptions!

Apply three-point estimating to address the uncertainties. Do not just blindly add contingencies—use standard deviation instead. Adjust the estimates as your assumptions get validated.

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