Introduction to Agile Estimation

What is it and how is it used.

What is Agile Estimation?

  • Agile estimation is a framework for estimating effort in a software project.
  • Independent of methodology (Scrum, Kanban…)
  • Not developer focussed

What is meant by Estimation

If we take a look at the definition of the word ‘Estimation’:

Estimation (or estimating) is the process of finding an estimate, or approximation, which is a value that is usable for some purpose even if input data may be incomplete, uncertain, or unstable.”

wikipedia

By definition, an estimation is always going to be inaccurate, it is just an approximation based on what can (and often will) be incomplete or unstable information.  

The problem is that when you are asked for an estimation, the person asking will not treat your response in this way (as an approximation)and will also not consider that you are possibly giving your estimate based on incomplete or bad data.

This can be dangerous as they will walk away thinking that your estimation is actually a firm and stable date/time when the thing, feature or product will be delivered.  And when the delivery is hours/days/weeks later than your estimation suggested, it can reflect badly on your ability in whatever role you hold.

This is the problem with estimations!

Estimation example based on data

The below graph shows the path of hurricane Florence in 2018:

The graph has been labelled with the day and time that the hurricane is expected to be in a certain place following an estimated trajectory.  On 8pm on Monday night we can see that the margin for error is very narrow, as the meteorologist will have plenty of accurate data to back up their estimation for the hurricane’s behaviour:

As time goes on, and we reach the same time (8pm) 2 days later on Wednesday evening, we can observe that the margin for error begins to increase.  At this point the original and accurate data for Monday gives way to an approximation for the path of the hurricane in the future:

By Saturday for the same week, the margin for error has become much wider, as the meteorologist is further estimating the path of the hurricane based on information received almost a week before:

The meteorologist will re-adjust their estimate as time progresses and more information become available.  

By mid-week, the margin for error we see in the above image for Wednesday will narrow, and updates will be made throughout the week.