Or an estimation-less approach to software development
I’ve had too many conversations (and overheard a few) about re-estimating stories or “re-baselining” the effort required for software projects. The latest one was about when it might be a good idea to do this re-estimation, and how, and what Mike Cohn says about it, and so on. The logic appears to be that as you gain more knowledge about the software being built, you can create better estimates and thereby have better predictability. This post talks about estimates, how they are just another form of muda (waste) and what might be a better way.
First things first
Lets start with fundamentals again. In order to stay profitable and prosperous, a software products company must be competitive. If you do enough root-cause analysis, the only thing that can ultimately ensure this is raw speed. Hence, the only metric that matters is cycle-time and organizations must always try to reduce it.
OK, so now, the issue simplifies itself – all we have to do is look for constraints, remove them, and repeat – all the while measuring cycle-time (and thereby throughput). Simple enough! And in the first few passes of doing so, I first realized that if you must estimate things, use story points. Then I realized that estimation in general is a form of muda – and converting from story-points to real-hours at the start of each iteration is a really stupid waste of time.
Even less muda
Now, having said all that, we can move on to the point of this post. I’ve come to realize there is a better way. One which achieves the goal of faster throughput, with less process and less waste. Eliminate estimation altogether. You don’t even need story points anymore. Here’s how it works -
Take a list of requirements. Ensure they always stay current – you know, by talking with the stakeholders and users and all the other involved parties. Ensure it is always in prioritized order – according to business value. Again, not hard to do – you just need to ensure that the stakeholders are as involved with the product development as the rest of the team is.
Next, pick a duration – say a couple of weeks. If in your business, two weeks is too short (you’re either a monopoly or you’re on your way out) then pick what makes sense. Pick up the first requirement and break it down into stories. Here’s the trick – each story should not be more than 1-3 days of work to implement. In other words, each story, on average, should be about 2 days of development time. Simple enough to do, if the developers on your team are as involved in the process of delivering value to your customers as the business is. Pick the next requirement and do the same thing, keep going until your two weeks seems full. Do a couple more if you like. Ensure that this list stays prioritized.
Then, start developing. There is no need for estimation. Sure, some stories will not really be 2 days worth – break them down when you realize it. Sure, you need good business-analysts and willing developers. You’ve hired the best, right? Next, as business functionality gets implemented to the point where releasing it makes sense, release it! Then, repeat.
What (re) estimation?
In this scenario, there really is no reason to do formal-estimation at all. Sure, super-high-level sizing is probably still needed to get the project off the ground, but beyond that, there is no need to do anything other than deliver quality software, gather real-user feedback, and repeat.
Now come the questions of how to say how much work is done, or when a certain feature will be delivered. The dreaded “how much more work is left” questions. The answer in this new world is simply = 2 days * number of stories in question. (Remember the average story size?) Many people like to track things, but measuring actuals is also muda.
The important thing is of course to not look too far ahead. In today’s business environment, the world changes at the speed of the Internet, so luckily this works to our advantage. Whenever something changes, you just re-prioritize the list of stories. This process is not only much leaner, it is also much simpler.
Let’s come back to the issue of re-estimation. People cite the fact that during the start of a project, there isn’t enough knowledge to truly estimate the high-level requirements. Then, as the project proceeds and they learn more, they seem to want to re-estimate things. I ask, why bother?
The key here is to recognize that “accurate” estimates don’t deliver any business value. It is only important that complex requirements are broken down into incremental stories and they are implemented and released quickly.
The real benefits
The fact that this saves time and effort is actually just a good side-effect. The real value comes from being able to truly stay in control of the development process. Tiny stories allow you to change them when required, pull them from the backlog when needed, or to add new ones whenever business demands it. It also lets you move faster because it’s easier to write code in small incremental chunks, testing is easier, and pushing small releases out to users is easier.
And finally, by imposing the discipline that each story be small, it ensures that people think about the requirement deeply enough before coding begins. It also forces the team to break down requirements into incremental pieces and totally avoids never-ending stories that always have a little bit left to complete.
This allows the whole process to be streamlined. It allows the team to focus on just what the users cares about (working software at their fingertips), and not on all the meaningless artifacts mandated by many methodology books (and indeed unenlightened management). Also, in this manner we handle the issue of estimation and re-estimation. In a zen-line fashion, we do it by not doing it.