The Evils of Percentage Complete
Many project managers and indeed most software tools ask for task updates as “Percentage Complete”, and this can cause all sorts of issues. So here are the The Evils of Percentage Complete.
Percentage Icons
Personally, I have no issues with “Percentage Complete” but only if it is either 0%, 100%, or calculated accurately. Here are some of the issues……
- People will lie! (or stretch the truth to suit their circumstances!) Given a 4 week task, after 1 week the task owner is asked for an update. A reply of 25% should be treated with suspicion! It is so tempting to tell people what they want to hear! A good task owner will give a detailed report on progress rather than guess at a percentage. A good project manager will ask better questions…..
- There are really only a few answers to the question. 0, 10, 25, 33, 50, 66, 75, 90, and 95% completed. MS Project only allows you to easily enter 4 of these from icons. Although these will give a rough idea of task progress (if true) it will only ever be a rough idea (unless it is 100%!)
- Tasks are both work and duration. A task may have 8 hours of work, but cover a duration of 4 days. When asking for percentage complete – do you mean through the work? or through the duration? What does the task owner think you are asking for? and what do they actually report? In this example of 8 hours work and 4 days, is the work split evenly through the duration at 2 hours every day?
- Work may not be split evenly through the duration. Typically there is more ‘work’ being done later in the ‘duration’. As an example, students may do their assignments at the last moment. Despite having 3 weeks to write them up! Or sometimes the work is split into several chunks through the duration. Understanding how the work is spread through the duration is vital if asking for percentage complete. This is referred to as the ‘work profile’ or ‘work contour’.
Work Profiles / Work Contours
In the following graphs, a 40 hour task originally takes 5 days (8 hours a day). Different ‘Profiles’ or ‘Contours’ of work are then applied.
Flat Work Profile
Firstly, our student example, of more work being done later on. Note how since little work is being done in the first days, the duration extends to 10 days to maintain the 40 hour total.
Late Peak Work Profile
Secondly, a ‘Bell Shaped’ work profile, where work is concentrated in the middle.
Bell Work Profile
and finally a ‘Double Peak’ profile.
Double Peak Work Profile
When using MS project, be careful to ensure that either ‘work’ or ‘duration’ is fixed, as applying these profiles will change one or the other!
In summary, never ask for “percentage complete” – as there is evil at play in the answer you receive. (The devil is in the detail!)
Give people time to work out their tasks statuses. Ask for how much work is completed, and how much work is yet to complete. make sure that you ask for both ‘Work’ and ‘Duration’ estimates. Ask for the spread of work through the duration. Request revised estimates as the task becomes current. Ensure that you know how to use MS Project correctly!
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