Backlog Grooming #2: How Small Is Small Enough?

As already discussed (click here for the previous blog post), Backlog Grooming is a workshop held to take large backlog items and slice them down into smaller pieces. More specifically, we discussed the three major goals of Backlog Grooming:

1. Estimate backlog items that have no estimate
2. Correct estimates that appear to be considerably off target
3. Discuss backlog items and divide them into smaller component pieces (slicing).

In this blog post, I want to discuss how we know how small to make our backlog items before we stop grooming them and move on to something else. If the backlog item is too large at the beginning of the Sprint, we run the risk of problems during Sprint Planning and during the Sprint. On the other hand, if we groom the item too small, we’re wasting time discussing something that can be easily dealt with in Sprint Planning.

Many experts currently agree that the “right” size for a backlog item is one that 2 or 3 people on your team can complete in less than a week (this concept, getting people working on one backlog item collaboratively is called “swarming”). This maximizes the Scrum team’s flexibility (small backlog items are easier to “fit” into a Sprint should some re-planning be necessary during a Sprint) while still allowing the team to do “functional” slicing during Backlog Grooming (as opposed to solving the backlog item, again see here).

So, what’s small enough that 2 or 3 people on your team can finish an item is less than a week? That will have to be up to your team. Every team is different; the best thing to do for a new team is let them make their best guess and then look at how it worked out at Sprint Retrospective (then, you can look at the Sprint Burndown and see how long each backlog item took to complete from the first day to the last). If the backlog items are taking too long, slice them down further. Eventually, the team will get an idea of the proper size based on the story point size they are putting on the backlog items (for example, 5 point items may seem too big – then the team knows to groom to sizes of 1, 2,  or 3 story points).

In Backlog Grooming, once a backlog item is groomed down to the “ready” range, stop. Don’t groom it further. Any remaining discussion can wait until Sprint Planning. Do not slice the backlog item into tasks. Move on to another backlog item.

In the next installment, we’ll talk about how many backlog items you need to slice before you should stop hold backlog planning meeting during the current Sprint. If you can think of additional topics you’d like to see me write about, please let me know.