Where estimates can go wrong (and how to fix it)

 •  Filed under Posts, Agile

Estimating. It's a word that can strike fear into people who are new to the realms of programming, project management, freelancing and other careers. The daunting prospect of estimating the length of time at which you will be able to complete a set piece of work.

I have over ten years experience in the realm of software development and sometimes I still get it wrong. I've seen developers get their estimates wrong by a couple of weeks and project managers miss their target deadline by months. So why are estimates so hard then?

The first reason is that the estimate is based on a bigger block of work, rather than multiple smaller ones. Estimating a project from just an outline of the project is a rookie mistake. When you estimate on a large single block of work, you are basically playing a guessing game. In fact your estimate is always going to be wrong when you do this.

Instead, break your big block of work down into smaller blocks of work. The more granular you get, the easier the estimate is going to be. It won't always be correct, but your estimate will be more accurate.The second reason is information. We are limited by our little brains in how much information we can retain when estimating on a project.

When it came to estimating on projects for ERP software customers, I had to remember that different customers had different workflows in their systems. No two systems were the same. I had to factor in that a customer will have specific workflows in their system that I need to either work around or work with. This job was made a lot easier by the fact that I used notes that I kept on each customer's system so that I was ready to make better estimates in the future.

Now I know this might not be easy to do for a new project where you have little information, but carrying any information that is relevant from one project to the next is going to make estimating on blocks of work a lot easier.

Estimating isn't a black art, it's simply something that requires you take the time to break blocks of work down into smaller chunks and if you can, have the right information at hand to make better estimates on those blocks of work.