Schedule estimation is a process that needs gradual refinement, to be done in several phases of the project development. Each project estimate should be refined to give a converged estimate towards the project end.
When framing plans before starting a project, there is insufficient information to estimate with any degree of accuracy. In this article at The Project Risk Coach, Harry Hall explains ways to combat project estimation challenges and suggests some techniques to respond to a project estimate.
Boil Down Estimates
A wrong or extended estimate leads to expanded work to fill the allotted time. Padded estimates, where the team members deliberately overestimate to keep enough time in hand, are an enduring challenge. The results are degraded quality or rework, high cost, and adverse impacts on the schedule. Therefore, the author suggests comparing actual time to the estimated time. Here are three techniques to draw a right estimate of the project schedule:
- Analogous Estimate: In this technique, the project manager looks for a similar project in the past and estimates similar duration with appropriate adjustments. The author suggests using this technique at the initial stage or early planning.
- Detailed Estimate: This one is the most suitable technique that involves estimating work at a task level to provide a summary estimate. Use this technique after completing the ‘work breakdown structure’. The technique takes time but gives accurate results.
- PERT Technique: This technique is a combination of three estimates including pessimistic, optimistic estimate, and most-likely estimate. Using a weighted average formula, calculate the expected value that is expected = ((Pessimistic + 4 (Most Likely) + Optimistic) / 6). The technique is apt for estimating a project for which you have no prior experience.
Click on the following link to read the original article: http://projectriskcoach.com/improve-schedule-estimates/