I am writing a course on earned value management and have been searching everywhere for an article on measuring % complete. I couldn’t find one so I thought this would be a valuable contribution.
The main objective of earned value management is to produce an objective assessment of progress to compare with the plan and the expenditure. People are notoriously optimistic at estimating progress on a project activity. So let’s see if we can define some more accurate way of measuring progress.
1) The most accurate method is physical percentage complete based the number of items completed. For example if we have 100 meters of cable to lay and we have done 50 meters the % complete is 50%. This is the most objective form of progress assessment but only applicable to a small number of activities.
2) The next best method is defined milestones. For example a drawing or report is defined as 50% complete when drafted, 70% when it has completed internal review and 100% when signed off by the customer. These sorts of rules are applied consistently across the project but are still open to some subjectivity. Sometimes we limit the choice to 0% (not started), 50% (started) or 100% (complete) however this can distort the reporting if a lot of tasks all start at the same time or take a long time to complete. So it is best to use small tasks for this approach.
3) The next best approach is to collect remaining durations. We do this by asking package managers how long it will take to complete some work. It is generally accepted that people are better at estimating how long it will take to finish then they are at estimating percentage complete. For a simple task with uniform resources this can be calculated from the duration. For example 10 days and we have completed 5 days of work but estimate that there are 6 days left then the
% complete = Actual Time Elapsed / (Actual Time Elapsed + Remaining Duration) = 5 / ( 5 + 6 ) = 5 / 11 = 45%.
If the task is does not use uniform resources then we can calculate the % complete from the estimate to complete (ETC) buy and the actual cost (AC) to date
% complete = AC / (AC + ETC)
So for example is a task 100 hours of work planned, and we have spent 50 hours working (AC) on it and estimate that we have another (ETC) 60 hours left to do. Then we get
% complete = 50 / (50 + 60) = 45%.
To use this technique you don’t tell the package manager what the actual cost to date is, otherwise they just subtract this from the budget to give you an estimate to complete.
This is a simple but effective way of reducing the subjectivity in estimating % complete.
4) Apportioned Effort is often used for overhead activities like project management. I uses the percentage complete for the physical deliverables to estimate the percentage complete for the project management work. If the physical project is 50% complete then the project management task is 50% complete.
5) Level of effort is used for fixed cost such as project office building or security. These earn value at the planned rate and will not contribute to a cost or schedule variance but can cause the project to overspend if it is extended.
Thanks to Vasil Tsakov for helping check these equations