Thanks to Flowing Data for introducing me to Guesstimate – an online tool that allows the inclusion of uncertainty or confidence intervals inspreadsheets.
One of the commentors on the article highlighted that he used it to how long it would take to take down the Christmas Tree, which even includes the total time spent complaining and procrastinating (at least 35 minutes, apparently).
It reminded me of the time I was given my first large project to manage at work. I naturally think in terms of critical paths, and I found breaking the project down into smaller tasks and working on the order fairly straightforward.
But when it came it to resource planning, I had to plan the number of staff I would need working on each component of the project to meet the deadline.
The key to this was knowing how long would each task take.
When I asked others on their approach, they take an average time based on previous projects. They didn’t work in minimums and maximums, which makes it difficult to work out a critical path.
Workers aren’t machines, there are daily variations in productivity, but obviously the average is meant to take this into account. But this assumes that the averages that overestimate and understimate will cancel each other out, and I imagine this is rarely the case.
Unless I’m missing something, using averages doesn’t seem efficient to me. Alas, it probably works in the world of resource management (as well as disseminating statistics), because, as the original article puts it:
“[By] ignoring the uncertainty, you end up with a result that seems concrete but it’s actually more squishy.”
Anyway, I like the approach of Guesstimate, which is designed to make you think about uncertainty. I’ll try and use it the next time I plan a large project.
PS: One of my goals for 2016 is to blog more. Can you tell?