Estimating with relative sizing

As we learnt at the GDS Academy, a key part of working in an agile way is building a shared understanding between the team undertaking a task. We decided to put one technique for doing this into action at the September meeting of the Future Forum.

We used the example of preparing various meals (from beans on toast to a 10 item buffet for 30 people) to practice estimation through relative sizing. Estimation is the process of a team assessing how much work a given task (or user story) will take to complete. This is not measured in hours or cost, but taken in the round and given a number (or story points).

The next task is then sized relative to the first – is it bigger or smaller, harder or easier? This is not an exact science and the aim isn’t to pick the “right” number, but to have a discussion that helps the group understand what is involved to finish the task and whether they have what they need (skills, materials or logistics) to get it done.

The Product Owner (PO) is key to this process. They clarify the vision for the product by answering the team’s questions and setting out their expectations for success. This ensures that everyone is on the same page, expecting to produce the same thing. It avoids a situation where the team might think they’ve completed the work, without delivering a key component that the PO hadn’t clearly specified, and therefore the work is rejected.

As we worked through the task, the group aimed to build consensus among themselves about how to rate each task. We used a planning poker technique, where everyone held up a card with the number they thought the task represented as a starting point, and then discussed and justified their choice. After the discussion another round of voting was held and after repeating this process sometimes several times, opinion converged around a single number.

Whilst this may be a time consuming process to go through for all activities and perhaps less necessary when a team is more familiar with one another and the type of work they’re doing, we could really see the value for this approach to new projects, with new people, to build that shared understanding.

Watch out for planning poker cards coming soon to a meeting near you!