Agile Story Points – Size Matters
The primary unit of work in Agile is the Story. There seems to be a lot of debate around story points and what they actually mean. Do points signify time? Not really, although every team I’ve been on has, over time, had a rough correlation with points and time - velocity. Do they signify the amount of effort needed to complete? Kinda? While it is a bit of both neither of these concerns, time and effort, is the actual purpose of assigning points to a story.
Story Points:
The true value of assigning points to a story is to flush out discussion. If everyone is voting a similar number of points there may not need to be much discussion but, if the points are all over the place… let’s chat this out.
Let’s assume the team is refining a story and the description is clear and the Acceptance Criteria seems well understood.
Scenario 1:
All team members but 1 vote to assign 3 points to the story and the 1 outlier votes for 2 points. In this case, it appears that everyone truly has their head around the story and it is quickly assigned 3 points. There’s not much use in haggling over 1 point: Next!
Scenario 2:
One team member votes for 1 point, 2 members vote for 3 points and the last member votes for an 8! What we see here is that even though the description is clear the team knowledge and concerns may be disparate. This prompts a conversation, mainly with the team members that are voting 1 and 8. The member that voted 8 brings up a good point that no one else had considered and the team asks the product owner (PO) a clarification question and updates the acceptance criteria with the answer. Then, when everyone is on the same page with the description and updated acceptance criteria all team members vote again and it’s a unanimous 3 points. Or, the discussion could have easily resulted in the creation of a preceding spike or a separate story to cover concerns brought up by the team member that voted 8 points.
The most important part of this interaction has little to do with the final number assigned but that folks really engaged each other and had the appropriate conversations to clarify the work necessary to complete the story.
Points vs. T-shirt Sizes:
Points vs. T-shirt Sizes:
Some teams use the Fibonacci scale (1,2,3,5,8…) to size a story and some use T-shirt sizes (S, M, L, XL) and they both do a great job promoting discussion. T-shirt sizing discourages the overzealous manager types from tallying story points and putting pressure on a team when velocity changes. On the other hand, using points can help a team understand their own velocity and make more meaningful sprint commitments. Points and Sizes are primarily for the team’s own use. Points should NOT be used to ‘manage’ – punish or reward – a team’s performance.
Story Points and Sizes do matter but, not for the obvious reasons. Remember in Agile it is conversations over documentation and the simple act of sitting down as a team, mentally walking through the steps to accomplish a story together and engaging in debate is where we find the true value.