A newer version of this post is at Improve Your Estimation Skills in the Time Management Tips section
Most of us are really bad at estimating how much time something is going to take and without good estimates things take longer then planed, we spend all our time fighting to save our schedule and productivity goes down the drain – But there is a solution, just follow those easy steps to become better estimators:
Step 1 - Break down projects into small tasks
The biggest problem with estimation is that people are really bad at estimating big things, ask a carpenter how much time it’s going to take to build a piece of furniture and you’ll get a widely inaccurate answer, but ask how much time it’s going to take to glue two pieces of wood together and the answer will be surprisingly accurate.
Every big, impossible to estimate, project is made out of a lot of tiny easy to estimate steps, break a project into those small steps, estimate each step separately and sum up the estimates and you’re already better off than 90% of people.
As a rule of thumb, if a single task takes longer than one work day you should break it down into smaller tasks.
Step 2 – Take unproductive time into account
The second biggest problem that causes bad estimations is that we are not working all the time, a lot of our work time is taken up by non-productive activities like e-mail, meetings and being interrupted by coworkers, in most workplaces we spend less than half our time actually working, if you have a bad boss of bad coworkers this can get much worse.
To compensate just multiply all your estimates by 3 (obviously the number changes from person to person and from workplace to workplace but 3 seems to be the magic number that cover most cases).
Step 3 – Things will go wrong, be prepared
The third problem is that sometimes some tasks take much longer than planned, some technology that you depend on just doesn’t work, one of your tools breaks down or some material you need just didn’t arrive.
You solve this problem by adding extra time on top of your schedule (and on top of the time you’ve added in step 2), this extra time is typically between 10% and 200% of the total project time depending on the project – the more unknowns there are, the more unreliable or experimental technology you’re going to use and the more different this project is from your previous project the more extra time you’ll need.
You should look at how much extra time you needed in similar past projects to decide how much extra time you need.
Step 4 – Learn from your mistakes.
And last but definitely not least, you need to learn from your mistakes and improve the two skills needed for step 1, breaking down large projects and estimating small tasks.
You have to keep a record of everything you do - so that when you forget some step when you brake the large project into small tasks it will be the last time you forget this step, the next project you can just go over the list of things you forgot and make sure they are taken care of.
You also have to keep a record of how much time each task took – and after each project you must review your original estimates and the actual times so you’ll make better estimates for the next project.
This is where good time tracking software can be really helpful, and (yes, this is a shameless plug for my own software) yaTimer – my time tracking software let’s you quickly add tasks, record estimates and has a report that shows you just how accurate (or inaccurate) your original estimates were.
If you follow those four simple steps (especially step4) after a few projects you will become surprisingly good at estimating how much time projects take, you will gain confidence that your estimations aren’t pulled out of thin air and you will have better schedules.
posted @ Tuesday, July 28, 2009 4:56 PM