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Relative Estimates

26 May 2016

Saumya Nigam
Societe Generale


In my article “Why Estimate?” I discussed getting clarity on who uses estimates and for what purpose, and what estimates are not for. As discussed, we don’t need to aim for absolutely accurate estimates. So the obvious question is, what in fact are we looking for?

The answer is relative estimation.
 

What is relative estimation?

Let’s start with simple question, “Is 5 big or small?” The answer is obvious: “It depends.” It depends what we are comparing 5 against: If we are comparing against 2, 5 is big; if we are comparing against 8, 5 is small.

Another question pops up: What is “5”? Is it time needed to complete story? No, here 5 is how complex this story is compared to another story, which the team has already estimated.

This holds good for experienced teams, but what about the team that is doing this exercise for the first time and has no base of comparison? For these situations, it is recommended that teams pick one story that is not too simple and not too complex. Associate a level of complexity, say “2” or “3,” with that story. Now pick other stories, compare them with that base story, assess whether they are more or less complex, and associate a complexity with the stories.
 

Conclusion

Absolute estimate Relative estimate
Aiming at accuracy Aiming at the purpose of estimation
Looking in the solution space Looking in the problem space
Needing in-depth knowledge of code base Needing clarity on the problem to solve
Driven mostly by the individual Driven by the team
Knowledge- and skill-driven Comparison-driven
Need ~80% clarity on how to do it Need ~25% clarity on how to do it
Need effort on prototyping for unknown areas No prototyping effort needed
 

What comes next

Another question pops up regarding predictability, which is how a PO or manager would guess how much the team will deliver in a given sprint/release, so they will plan accordingly. The answer in Scrum/Agile is “story points” and capacity/velocity,” which I will discuss in a later article.
 

Opinions represent those of the author and not of Scrum Alliance. The sharing of member-contributed content on this site does not imply endorsement of specific Scrum methods or practices beyond those taught by Scrum Alliance Certified Trainers and Coaches.



Article Rating

Current rating: 4.7 (7 ratings)

Comments

Rohit Ratan Mani, CSP,CSM, 5/26/2016 4:58:16 AM
Nice article.
Saumya Nigam, CSM, 5/27/2016 1:54:20 AM
Thanks Rohit

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