[Int. developer’s office. Developer sits at a desk that faces the wall. Two of the monitors on Developer’s desk are on stands, if you look closely you see that the third is balanced on the box set of The Art of Computer Programming, which is still in its shrink-wrap. Developer notices you and identifies an opportunity to opine about why the world is wrong, as ever.]
Every so often, people who deal with the real world instead of the computer world ask us developers annoying questions about how our work interacts with so-called reality. You’re probably thinking the same thing I do: who cares, right? I’m right in the middle of a totally cool abstraction layer on top of the operating system’s abstraction layer that abstracts their abstraction so I can interface it to my abstraction and abstract all the abstracts, what’s that got to do with reality and customers and my employer and stuff?
Ugh, damn, turning up my headphones and staring pointedly at the screen hasn’t helped, they’re still asking this question. OK, what is it?
Apparently they want to know when some feature will be done. Look, I’m a programmer, I’m absolutely the worst person to ask about time. OK, I believe that you might want to know whether this development effort is going to deliver value to the customers any time soon, and whether we’re still going to be ahead financially when we’re done, or whether it’d be better to take on some other work. And really I’d love to answer this question, except for one thing:
I have absolutely no idea what I’m doing. Seriously, don’t you remember all the other times that I gave you estimates and they were way off? The problem isn’t some systematic error in the way I think about how long it’ll take me to do stuff, it’s that while I can build abstractions on top of other abstractions I’m not so great at going the other way. Give me a short description of a task, I’ll try and work out what’s involved but I’m likely to miss something that will become important when I go to do it. It’s these missed details that add time, and I don’t know how many of those there will be until I get started.
The proposed solution
[Developer appears to have a brainwave]
Wait, remember how my superpower is adding layers of abstraction? Well your problem of estimation looks quite a lot like a nail to me, so I’ll apply my hammer! Let’s add a layer of abstraction on top of time!
Now you wanted to know how long it’ll take to finish some feature. Well I’ll tell you, but I won’t tell you in units of hours or days, I’ll use BTUs (Bullshit Time Units) instead. So this thing I’m working on will be about five BTUs. What do you mean, that doesn’t tell you when I’ll be done? It’s simple, duh! Just wait a couple of months, and measure how many BTUs we actually managed to complete. Now you know how many BTUs per day we can do, and you know how long everything takes!
[Developer puts their headphones back in, and turns to face the monitor. The curtain closes on the scene, and the Humble(-ish) Narrator takes the stage.]
The observed problem
Did you notice that the BTU doesn’t actually solve the stated problem? If it’s possible to track BTU completion over time until we know how many BTUs get completed in an iteration, then we are making the assumption that there is a linear relationship between BTUs and units of time. Just as there are 40 (or 90, if you picked the wrong recruiter) hours to the work week, so there are N BTUs to the work week. A BTU is worth x hours, and we just need to measure for a bit until we find the value of x.
But Developer’s problem was not a failure to understand how many hours there are in an hour. Developer’s problem was a failure to know what work is outstanding. An inability to foresee what work needs to be done cannot be corrected by any change to the way in which work to be done is mapped onto time. It is, to wear out even further an already tired saw, an unknown unknown.
What to do about it
We’re kindof stuck, really. We can’t tell how long something will take until we do it, not because we’re bad at estimating how long it’ll take to do something but because we’re bad at knowing what it is we need to do.
The little bit there about “until we do it” is, I think, what we need to focus on. I can’t tell you how long something I haven’t done will take, but I can probably tell you what problems are outstanding on the thing I’m doing now. I can tell you whether it’s ready now, or whether I think it’ll be ready “soon” or “not soon”.
So here’s the opportunity: we’ll keep whatever we’ve already got ready for immediate release. We’ll share information about which of the acceptance tests are passing, and if we were to release right now you’d know what customers will get from that. Whatever the thing we’re working on now is, we’ll be in a position to decide whether to switch away if we can do some more valuable work instead.