Estimation of an IT project is not a pleasant exercise. However, it is part of project management.
Usually, the pain points are
- Depending upon the role, we come up with own version of numbers.
- Project Bidder, Project Governance intend to move the numbers down; Black sheep intends to move it north
- Estimation implicitly mean a commitment to management
- Estimation is made without clarity of requirements
- Estimates are subject to stakeholders interests and personality
Some principles of estimation practice:-
- Parkinson law – Work shall fill the time allocated for completion.
- Today’s project is Tomorrow’s legacy
- Quality/Reliability of Estimation cannot be better than the requirements
- Poor congruence of stakeholders is a perfect recipe for disaster
- Often one fails to understand the difference between –Effort and Duration in estimation.
- Cost and Effort are associated with Work Breakdown structure while Duration associates to Critical Path.
- Cost – Money Spent (Unit – Currency)
- Effort – Work Time for a task (Unit – Person-Hours)
- Duration – Calendar Time (Unit – Days)
Here’s one technique for estimation.
- Discuss with responsible person of a task to identify – effort required when it’s all roses with no thorns in the path. Let’s call it – Optimistic (O) number.
- Identify the effort when we, it’s all desert with no hope of oasis. Let’s call it – Pessimistic (P) number.
- Pinch yourself, it’s a real world. Both of the above cases are unlikely, Identify the effort. Let’s call it – Realistic (R) number.
The estimated number (E) is (O + 4R + P)/6 with Uncertainty(U) as P – O.
Always Report Estimated number E with Uncertainty U. Plan and be prepared for, Uncertainty U.
A yardstick for self-review of estimation maturity :
Review and update your Estimates E and Uncertainty U in iterations; Uncertainty U should decline.