Initial estimates of the amount of work for a project or idea lacks detail. Attempting to forecast using historical rates would be in error if:
1. The granularity of work breakdown differs from historical samples.
2. The project isn’t completely fleshed out as to what features are required
3. The project ignores system and operational issues. New environments, changes in current environments, security or performance audits and requirements.
If every project needed to be completely understood with every detail, then forecasting would take too long. The rate of failure in delivery of waterfall projects howed that even attempting to completely design and understand projects doesn’t improve delivery likelihood.
Tracking the increase in scope and the causes for previous projects allows projects at an idea level to forecast with some certainty of likely scope increase. The recommended technique is to keep clear records of the amount of total scope for each project, categorized by work-item type. Some categories we recommend are:
1. Split (straight split of known work)
2. Discovered Scope (scope found only after deling into the detail)
3. New Requirement (nothing to do with the original ideas, added features)
4. Adopted work (work the team took on but isn’t actually part of a project)
By tagging each backlog item with these tags, a growth-rate from an original amount of work can be computed. This adjustment can be applied to new ideas when quantitatively forecasted. These metrics are also good to put targets around. None of these items are bad by default, its just good to know where the scope increases are coming from and to manage/consider them when forecasting proposals.