Effort vs Complexity
I've read several books on Scrum so far, which mention that the team should do effort estimation at Sprint Planning. One exception is Sutherland's latest book, which expressly states that we humans are awful at estimates, and proposes instead to use some non-dimensional complexity indicators (like 1,2,3,5,8,13,21 - he proposes using Fibonacci sequence as one most close to our perception of the world). This makes sense to me, and in the end, when we know the velocities after several sprints, we'll do much better estimates. The question is, is it really needed to estimate efforts in man-hours as the other books suggest? Would the contrary be a violation of Scrum spirit?
Scrum is agnostic about how estimates are sized. The Fibonacci-style sequences you mention are widely considered to be good practice, and find expression in the "planning poker" cards that are commonly used to facilitate relative sizing.
Posted By Vladimir Zakharov on 10 Feb 2015 11:21 AM
I've read several books on Scrum so far, which mention that the team should do effort estimation at Sprint Planning.
Estimation, whatever unit used, should be done during Product Backlog refinement sessions and not just during Sprint Planning Meeting.
It is too late if the Dev Team "discover" Product Backlog Item in the Sprint Planning Meeting.
Olivier, could you provide a source please? From what I've read so far, refining the Product Backlog is part (actually, the first part) of the Sprint Planning meeting. And I've never heard of "Refinement Sessions" as part of Scrum specification.
Just read in Scrum - A Pocket Guide by Gunther Verheyen that PB Refinement is one of good practices, but not a regulated part of Scrum.
Product Backlog refinement is provided for in the July 2013 Scrum Guide. It isn't enumerated as a time-boxed Scrum Event, rather it is contextualized as an ongoing process.
I think of Backlog Refinement (Formerly known as Backlog Grooming) as a required *activity* in Scrum but not a required event. It also has an associated time-box for that activity --- so see the Scrum Guide for more specifics on refinement.
For some backlog refinement tips, see here: