Estimating Software Development
Anyone who knows me will know that the title of this post is meant as a bit of a joke. For software development, it is my experience that estimating** is rarely useful and always easy.
Well… a little clarification: estimating is NEVER useful but ALWAYS easy the way I have typically seen it done, which uses the WAG* method of providing some numbers that seem plausible and that will allow the decision makers (stakeholders and managers) to approve the start or continuance of a project with a clear conscience. That is, when things sour later on they can always blame the developers for giving them inaccurate estimates (and not living up to their “commitments”).
And the developers can always blame the “requirements people” for giving them unclear, incorrect, or incomplete requirements.
And the requirements people can always blame the stakeholders for providing bad direction about what was important and the developers for not “understanding the requirements”, and so on.
Regardless of who is part of this process, it is one big happy circle of blame that lets us all do the wrong thing and still keep our jobs (not always happy for everyone, actually, and sometimes not everyone will keep their job).
I have simplified it here, but the basic idea is sound. As long as everyone is good at deflecting blame, and everyone is willing to continue on saying we’ll do it better “next-time” and after only a few people have been fired then everything is fine, right? Well, I don’t think it’s fine, of course – but many organizations seem to operate this way.
Let’s estimate a game of chess
Chess is a game that some of you may have seen. It provides a very limited environment with only 6 different and charming pieces that have very limited ways in which they can be used, and there are only two players. Simple. The whole game can be contained in an area of about a square foot or even less, and the complete rules can be written on the inside of the box lid. Just like Candy Land, it is very easy to learn and play. Not so easy to win, perhaps – but that makes it interesting enough to be an engaging game for some.
So, here is a description of a simple “project” and I need your estimate:
Win a game of chess. Losing is not an option. Tying is not an option. We will only make money if you win. If you don’t win, the company is at risk, and you will lose your job (and mine).
Also, I have a diagram of a chess game with the exact position of the pieces as required at the end of the game. To make money, it needs to end up just like the diagram.
Oh, one other thing: we don’t know yet who you will playing, but we’re pretty certain it will be someone who knows how to play the game, and might be pretty good at it.
That’s it! There are only a few requirements: That you win, and that the board matches the diagram I’ll give you. Easy!
What I need to know is exactly how much this will cost me. In this situation, cost is the number of moves you’ll need to meet the requirements. Oh, also, we don’t have the diagram yet, but we’ll have it soon. Still, you should be able to estimate it because it is basically the normal chess end-of-the-game arrangement with pieces here and there and so on, and you have the opponent in a checkmate.
Should be easy to estimate that, right?
Well, I hope you agree this is impossibly difficult, or actually: just plain impossible to do a meaningful estimate. First of all, there is not enough information to do a good estimate, and even if we had all the information, there are many variables and a lot of stuff we have no control over. How close do you think your end results would come to the requirements? Would you be willing to stake your job on making a decent estimate on a chess game in this situation? Well, as long as you could blame someone else and promise to “all do better next time” you’ll probably be okay. Or you could be a consultant and be paid and off to your next contract before someone actually has to play this game you helped them estimate.
Getting better at estimating is like pulling teeth
I hear it over and over: Our estimates were not accurate and we had a lot of trouble because of that. We need to get better at estimating.
It is similar in a way to saying “My tooth hurt, so we pulled it out. Now I can’t chew as well as I used to. We need to get better at pulling teeth”. What is the real problem? Shouldn’t we work on that instead? Hint: Getting better at pulling teeth is not it.
So what would you do to get better at estimating the game of chess, based on the basic scenario we described above? Could you get better at it? How good would you have to be before it had real value? Is it worth spending time on getting better at it? What is the real problem. Hint: Getting better at estimates is not a solution to anything because having bad estimates it not the real problem.
My suggestion: Stop That!
I haven’t seen much value in estimates. Actually, in the software development work I have done, I can’t recall any situation where estimates** of this sort were of value to the actual job at hand. Someone wanted them, someone saw value in them, and sadly – important decisions were made based on them. Do you think those were good decisions? People often tell me that “even though we know the estimates are inaccurate, they are better than nothing”. I prefer nothing, if there are better ways. There are better ways.
Almost everyone tells me that estimates** are very important, but estimates are often a blind spot hiding something of actual importance and value. This almost universal acceptance that estimates are important and useful is harmful. A predictive approach such as waterfall itself depends on estimates – and estimates are how we make the predictions. Don’t think “waterfall” and predictions are harmful? You probably should be reading some other blog.
Estimates** of this sort are based on guesses about the time needed to do work we don’t yet understand. Nothing about this gives me confidence that these estimates have value.
It seems I always make enemies when I suggest this, but that is not my intention. I want to do effective work on meaningful stuff – that is my intention. I don’t want to be spending time on work that has no value, causes misdirection and waste, and potentially destroys any chance of being effective. That is painful. There are MUCH BETTER WAYS to approach software development.
Do you need estimates?
It could be useful for you and your organization to question your use of estimates and explore new ways to think about your “need” for estimates.
One last thing: Do not ask me for an estimate on how long it will take to eliminate estimates from your process. It is too much like a game of chess, only very complicated.
Here is a start at clearing up our thinking. Let’s do a little thought experiment.
Which would better help if we have decided to eliminate estimates and find a better way in our organization? :
- Get rid of all developers
- Get rid of all upper management.
- Get rid of all upper management and developers
- Something else more realistic
Who is most insistent that estimates are important? Who do those people answer to? Are they going to fire you for questioning things like estimates? Are they open to scrutinizing the status quo or to examining why we do the things we do?
So what might be better?
What can we do instead of doing estimates?
Nothing. Don’t do estimates. Simple, clean, easy. But that is not the question we should be asking, and that is not what I am suggesting.
The correct question is: since we think that estimates are important, and you say that they are not, how can we develop software without doing estimates?
The answer is… Well, I suspect no one reads this blog, so that doesn’t really matter. This is just a clearing house for my thinking and has nothing to do with the reader. However, I am sure to write some stuff someday about ways to get things done without estimates, and I guess some of my earlier posts cover some of this thinking. If someone is actually interested and asks for me to cover this, I might get to it sooner. But I am sure you can figure it out without me – this is truly simple stuff. Read the Agile Manifesto and Agile Principles, and use them to invent better ways.
Another hint: Get good at frequent incremental delivery of useful software. That might be worth considering. That takes a LOT of experience and open thinking.
* WAG = Wild Ass Guess. A Wild Ass is a beast that is indigenous to parts of Africa and Asia. A Guess is a guess. Wild asses are about as good at making software estimates as anyone else.
** For the purpose of this article, the sort of estimates I am discussing are the estimates typically asked for on many projects where a list of features or functions are described and people are asked to come up with an approximate cost in time (working time or elapsed time) [sometimes it is phrased as “cost”, or “effort”] to do the work that will be required to provide the feature(s)/function(s)/capability(ies) being requested.
Disclaimer: There are many situations where estimates can be meaningful and useful. This article is about situations where I don’t think they are meaningful or useful.