It’d take me 15 min to reach train station – now this statement would be true if you have been to the train station before (in which case the activity estimate is relativity compared to previous one) OR you know all the factors that’d help you reach train station like signals, apartment elevators (if any) and so on. The point here is, absolute estimation in time is possible when all the supporting parameters are known and within control.

Now that probably is a story where the world operates under ideal conditions. The reality is different. Most (or may be all?) decisions mankind has ever made since stone ages, have rarely been free from dependencies. And the moment dependencies crop up, absolute estimates are prone to deviate. The catch is – human brain scientifically isn’t capable to catch those deviations. Read the scientific explanation HERE to know more.

So what’s the point again if we as humans are poor at absolute estimation? Well, drum rolls. Red carpet. Welcome ! Relative estimation, with emphasis on the word relativity. What is it? If you try looking up on google or credible websites in agile world like agile alliance, this is what you’ll find –

Relative estimation is one of the several distinct flavours of estimation used in Agile teams, and consists of estimating tasks or user stories, not separately and in absolute units of time, but by comparison or by grouping of items of equivalent difficulty.

To support this rationale, think of how how you decide what coffee cup size you’d want at the coffee shop –

When you see these coffee cup sizes, you don’t ask the barista if small is precisely 100 ml and if large is precisely 200 ml. What you do think however is, large is probably too much coffee coz it’ll be lunch in an hour, I’ll go small. What you’ve done in your head is called “relative estimation”

Another example is may be traveling from Sydney to Melbourne (since I am in Australia, but you will get the point). You may start by saying it is ~500 kms so the journey is going to be 10 hours and that’s what google maps tell you –

What you really encounter is live traffic conditions may be due to a crash, thanks to technology. So now you have a change in no. of hours it’d take. And suddenly the reality changes to this –

You may well decide to take a bathroom break, stop for your fav. maccas or a random sight seeing. All these parameters will constantly impact the no. of hours it’d take to reach Melbourne which was otherwise an absolute number at the trip start. And the no. of hours would differ every time those parameters come into play. It’s easier then to say, “I’ll be reaching in another 6 hours” based on the time and distance you travelled in the past. That exactly is relativity at play. So what’s the benefits if I have to constantly evaluate estimates? There are many –

Benefits of Relative Estimation

  1. It’s easy to compare – something being relatively bigger or smaller than something else.
  2. Shifting from “It depends” – humans know that absolute estimates are always prone to errors. A classic answer if you ask a software engineering team on how much time you think this would take, is, “It depends” and that is right, there is no pessimism or attempt to buy time. We don’t know what we don’t. That’s where the hesitancy. If you provide some facts behind that says, last time around, same activity took us 3 weeks considering we had some unknowns, so relatively this time around it’d take twice the time since we already have few tasks to finish. Perfect !
  3. Moving away from unrealistic expectation – People leaders or managers sometimes unrealistically expect that all milestones will be hit based on absolute numbers discussed at the start of the project, the point that is missed out here is reality is continuously impacting those numbers, so evaluating the change in time to hit the milestone is what will help over sticking to initial plan.
  4. Better accuracy – “Add some buffer just to ensure we meeting timelines” – sounds familiar? This is a teams best and honest way to say “we don’t know but we’ll put our best foot forward” and that again does not work. This is where relative estimation helps by bringing accuracy.

These are just some handful of benefits. There are plenty. Check out our other articles on some other agile methods, tools and processes you can pair up with relative estimation to get you most value.

Keep Learning!