Size, Layers and Intuition

As the holidays approach and the cold weather begins moving into Kansas City, it's a good time to reflect on our efforts and goals in the areas of custom software development and agile process coaching.

In the area of User Story Points estimation we made one seemingly subtle change in that we refer to the activity as "Sizing" a User Story rather than "Estimating". For us, it seemed to further focus the discussion on the size of a given User Story, especially when triangulating the story relative to other already-sized stories. This has been useful in a variety of ways, including helping move people past struggling to understand the concept of a story point.

We look at discussing and sizing a story in terms of the elements common to most stories (at least in terms of our software development) which tend to fall in the area of the classic three layers: UI, Business and Data layers. Traditionally, teams have relied mostly on free-form discussion and developer (sizer) intuition to determine point values and during triangulation. While we agree that expert developer opinion and intution is highly valuable, sessions can sometimes be prone to thrashing (excess discussion), fatigue and personality dominance.

When we conduct sizing (using the Planning Poker approach) sessions, we read a User Story card and then the customer answers questions from sizers (developers) until there are no more questions. This is fairly standard in most Planning Poker approaches. But instead of sizers flipping one card to reveal their overall size opinions, they use three cards. One for the UI layer, one for the business layer and one for the data layer. The idea is that since they are already thinking about the complexity and therefore the amount of work involved in implementing a user story and since they usually do this in terms of design,testing and development along the lines of the three classic layers of UI, business and data, we have them assign story layer point values (using the same point scale they would for overall story points) to generate discussion about differing opinions and to confirm assumptions even when their size opinions are similar the first time they flip their cards. In some cases, we'll even have the sizers shout out the objects (Forms, Reports, Classes, Controls, Tables, Stored Procs, Views, etc.) they had in mind across the layers and record those on the wall for a number of reasons, including for reminders of effort we already accounted for in sizing other stories. The resulting layer size opinions and object counts help with triangulation for an overall story size opinion. This is useful for current sizing sessions and for future triangulation as new stories are uncovered during subsequent iterations. The final consideration is developer (sizer) intuition. Even with object counts and layer assumptions in place, if the group feels that similar stories based on the above shouldn't share the same overall point assignment based on their gut that design, acceptance testing, etc. makes the story belong in another point column, then the story gets moved.

Doing the above does add some additional time to the sizing session but it also saves time by reducing thrashing and directing a portion of the discussion along the lines of the story layers. The net result is no more time is taken and a there is typically a higher degree of confidence in story sizes.