You Probably Suck at Estimating (And What You Can Do About It)

This post is part of a series about making better product decisions.

You probably estimate every day. How long will it take to build a given feature? What impact will it have on your customer base? How will it impact business outcomes?

It's too bad you probably aren't very good at it.

Don't worry. You aren't the only one. It turns out, we all suck at estimating. We just aren't very good at predicting the future.

The Heath brothers, in Decisive, summarize research that can help us get better at estimating. Often when we estimate, we make a single estimate. If you ask an engineer how long it will take to add a feature, they might answer three days. Or if you estimate the expected conversion rate of an email, you might end up with 3%.

Research, however, suggests that you can dramatically improve your estimates by predicting a range. What's the high end? What's the low end? Asking each question forces you to draw from different types of knowledge.

What's the shortest amount of time it's taken for an engineer to build this type of feature? What's the longest? The future probably falls somewhere in that range. This technique can improve your estimates by 70%.

You can also ask: What's the most likely outcome in this particular situation? What's the most likely middle point? Adding a best guess in the middle improved estimates by 98%.

You can extend this concept even further. Whenever you are trying to estimate something, spend some time doing a pre-mortem and a pre-parade.

If you work in an Agile environment, you are well aware of postmortems. So what's a pre-mortem? Pre-mortems force you to fast-forward in time and ask yourself, we built this feature and it was a disaster, what went wrong? Why did it take ten times as long? Why did it have zero impact on business outcomes? Why did it negatively influence user behavior? Pre-mortems help you tap into past experience to more accurately predict the low end of the range.

Pre-parades on the other hand, ask you to fast-forward in time and ask yourself, we built this feature and it was an overwhelming success, what went right? You were able to reduce development time by ten, why? You quadruped the expected impact on business outcomes and customer behavior? Why? Again, pre-parades help you apply your past experience to more accurately estimate the top end of the range.

So don't just rely on a single estimate. The next time you find yourself having to estimate something (which I'm sure will be later today), take the time to run through this exercise and predict a range.

Do you have experience predicting ranges? Please share in the comments.

P.S. I took a ten-day digital sabbatical this month to have this great adventure.

This post is part of a series about making better product decisions.