The perils of percentage availability...

 

Through education or experience most of us learn early in our project management careers about the dangers of using percentage complete for any activity where the work completed cannot be reliably measured. This is unfortunately the case for most knowledge-based work.

While a contractor can examine a wall being built and verify what percent of the work is complete based on how much of the wall has been finished, a development lead looking at the source code for a given function will be unable to come up with more than an educated guess as to what the true status of developing that function is. That is why we are encouraged to ask objective questions such as "How many hours of work is remaining?" or better yet, to utilize conservative reporting methods such as 0% and 100% or (for those in the agile delivery space) Not Done and Done Done.

So why wouldn't this also apply to resource availability?

Unless you are benefiting from either a project-oriented or a long lived team, chances are your team members will not be dedicated to your project.

I'm not referring to the normally expected non-project activities that everyone incurs such as department meetings, HR activities and so on. While there is an ebb and flow to those, there is usually a combination of historical data (e.g. at least 20% of the month before fiscal year end has been proven to be spent on annual performance review activities) and personal plans such as team vacation calendars to provide confidence about those estimates.

What concerns me is when a people manager gives me a percentage availability. "I can't provide Bob full-time, but I can give him to you for 50%". This occurs so frequently that we rarely challenge it unless we are sure that a staffing shortfall will critically impact our project's objectives.

But what does 50% of Bob really mean?

• Is it 3.5-4 hours per day, every day for the duration of the project?
• Is it Mondays, Tuesdays & half of Wednesdays for the duration of the project?
• Is it Mondays, Tuesdays one week and Wednesdays, Thursdays & Fridays the next week?
• Is it 75% time for half the duration of my project and 25% for the second half of the project?
• Or (and this is the most likely case) is it that at the end of the project, if I divided Bob's actual hours spent working on my project by the potential hours he might have worked if he had been allocated full time, it will be close to 50%?

And what will be the impact to your timelines and other project success criteria if you made the wrong assumption?

So the next time someone gives you a percentage availability commitment for a team member, ask a few questions to really understand how much time that person will be dedicating to your project and when.

If your body temperature is average but half of you is in a freezer and the other half is in an oven you aren't likely to be too happy!