How hard is it to estimate how long something will take? The answer is very hard! But why is this? Well, there are a few key factors. Mainly, the problem with time is that in a short space of it anything can happen. It is unpredictable. Estimating in time is risky. Secondly, people aren’t actually very good at estimating how long things will take. How many times have we heard “how long will that take?”, only to hear the reply “how long is a piece of string?”. Sometimes tasks are so massive, we just cannot begin to get our heads around it. People are, however, much better at measuring how complex a task is.
Let me explain…
If someone pointed at a messed up Rubik’s cube and asked me “Is that complex to solve?”. Personally, I am really not very good at those things, so I’d be like “Err, YAH!”. I don’t need to know much to know it is complex. Complex doesn’t mean ‘hard’. It’s not exactly ‘hard’, I mean it’s just moving some squares around, but its complex because it takes a lot of thought, and there are so many combinations to process as I move the pieces.
Now, if the same person then asked me “How long will it take you to solve that Rubik’s cube?” I would have absolutely no idea.
This is why in Scrum we measure complexity of work in story points as opposed to in time. Once the team understands the concepts around points and planning poker, they get pretty good at measuring complexity. It turns out it is a much more accurate measure of forecasting estimates than time alone ever will be, and this makes story points powerful.