Agile Estimation and Planning
Part 2 – Scope
At this moment, all I have is a cursory understanding of how a few pieces of work relate to one another. There are a myriad of activities that one could perform in support of a lawn. We’re going to focus initially on mowing.
One weekend not so long ago, I looked at a long list of activities I needed to work on, and was trying to figure out how much I could do with the time I had. One of the things that I have a pretty good handle on is mowing my lawn. My definition of “Done” was pretty basic: gas up the mower, make sure it was set to “mulch”, and wander the property until all the grass was a nice, mostly uniform height. On most weekends, using my self-propelled lawnmower, I have been able to complete that job in about 45 minutes.
“Ah HA!”, I hear you cry, “Time! Your one point lawn takes 45 minutes. I’ve cracked the code!”
Well. That’s nice. Good for you! But before you pat yourself on the back and start dividing my backlog into 45-minute increments, I’m going to wrinkle this up for you a bit.
Last summer, I hired someone to mow my lawn for me. Don’t judge. Work was demanding, and it was hot, and once you hire one of those guys, they keep coming back. So my point is this: Ed didn’t have a measly self-propelled walk-behind mower. No. He had one of those zero-turn-radius, stand/ride-behind monster machines that goes zero to sixty in about 2 seconds. He fired that bad boy up, and viola! My lawn was freshly shorn in 10 minutes!
So, let me ask you this: Did my lawn change size? If you are a proponent of a universal constant between time and size, then we’re in trouble. By your calculation, Ed’s performance has reduced my 1 point story to something under a quarter point.
I submit to you that my lawn is in fact, the exact same postage stamp it has always been. If it was 1 point before, it is 1 point now. But something is clearly different. Even I have to admit that 45 minutes vs. 10 is pretty compelling (or at least disheartening).
The difference has very little to do with the lawn itself. The difference is that Ed, with his superior machine is capable of delivering the same work in less time than me (or more work in the same time). If you assume a universal conversion factor exists, then you will need to gather two sets of estimates (mine and Ed’s), or at least pay attention to which one of us gave an estimate for a given lawn.
Or, maybe we try looking at this another way…
If you take my 1-point lawn and assume that every approximately 1-point lawn will take the same approximate amount of time (for me) then I can use that understanding to suggest how many 1-point lawns I believe I could fit into a weekend. Given what I know, I think I could complete approximately 16 points worth of lawn in a weekend. But my friend with the impressive hardware can do many more! The math whizzes out there have probably already concluded that Ed can do six 1-point lawns in an hour. So given an eight hour workday and two days in a weekend, he’s going to be pounding out 96 points worth of lawns every weekend. Those same math whizzes will point out that my sixteen-lawn estimate for myself is obviously under-represented. I should be able to do four lawns every 3 hours, so the same eight hour workday, I should be able to do 21 points worth of lawns in a weekend, and if I just did a little overtime, I could pull off 22!
Isn’t math awesome?
and Terrible?
Allow me to toss a little water on those flames of victory you’re dancing around. Unless you are going to work things out so those 21 lawns are placed end-to-end next to each other and set up my mower to be perpetually full of gasoline, I can’t possibly attain the number you’ve so carefully calculated for me. I will have to move the mower from one location to another. I have to refuel at every job. I have to stop to take a drink of water, or eat lunch, or answer a call. Your assumption of my velocity seems to be missing a few considerations.
Your assumption of Ed’s velocity is just as wrong, by the way. In order to move that behemoth of his, he needs to load it up onto a trailer and drive it to the next job site. Where would we account for loading and unloading time? Where do we account for the travel time between locations? What about bathroom breaks?
The capability of a team is made up of a lot more than just the sum of the hours of work they perform, or the number of hours we think they can give us.
