Wednesday, June 28, 2006

I'd rather be precise than accurate

I was listening to a podcast from the Agile Conference 2005 - a little old now but still very relevant. It was Arlo Belshee who mentioned that, in relation to project management and project execution, specifically software development estimates, he is more interested in precision than accuracy.
Sounds odd at first, but think about it. What this boiled down to was that if you are precise, that is you can do / estimate precisely the same way each time, you can make that more accurate as you go.
The analogy to a rifle range was made. If you are shooting at a target, and put five shots in the zone, just outside the bulleye, all one inch either side, then you're pretty accurate right? If you put five shots through precisely the same hole, a whole 12 inches away, you're precise but not as accurate. But at least now, you can recalibrate (or make improvements/allowances), one way only, and all of a sudden you're accurate as well. If you go again, and this time only four shots go through the same hole, and one is left by an inch, something else has changed - you're accurate (probably more so) but now, you're not as precise and you'll want to know, what happened.
My take on this is that if you are going to compare results from one timeframe to another, or across projects, it is not that relevant what the unit of measure is, or how close to some arbituary target it turned out to be (how accurate it was), but more so, how it changed since last time. What impact has changes in your environment had to your performance.
This has just had an impact on me as I attempt to work out some costs verses benefits, verses customer satifaction verses any other measure I choose to come up with for some business intelligence anaylsis I've decided, on the back of this article on Gantthead, I, as an IT Manager, should have a bit of a handle on. There are so many costs to take into account - and while of course I want to be as accurate as possible, what is more important than the overall cost figure and it's accuracy, is the precision of my measurements each week.
Accuracy, will no doubt come into the picture come budget season - another story. No good being precise and running out of money in December I guess.