I’ve been using the agile approach in one way or another now for the last eight years. There are so many different flavors of agile – but all rely on the team’s ability to make good decisions quickly.
Most teams need a method to evaluate, and fall to data that can be gathered and trusted, data like sales, or traffic numbers, or estimated hours. The trouble is, the real data can often lead to over-analyzing the problem when the goal is to evaluate a list of things relative to each other and move on to the task at hand.
Switching to a non-numerical system like T-Shirt sizing removes the implied precision of the numerical data, leaving the team free to think in a more abstract way about the size and complexity of a problem, and how those problems relate in size and complexity to other problems. This is important because we want these people spending their time on creating the actual solutions rather than arguing about them.
Most teams I’ve worked with use a three-bucket system of “Small, Medium, Large”, it’s very fast but it can lack granularity. Others have opted for a five-bucket system of “Extra-Small, Small, Medium, Large, and Extra-Large”, it seems to be a little better at dealing with granularity, while still keeping the process quick.
Obviously, non-numerical scales are less granular, and while they do speed up the process of assessment, it can come at the cost of accuracy. I’ve found the people most concerned with a slight loss of accuracy are usually one or two levels up in the organization and unfamiliar with the agile approach. They may not yet see the direct benefits to moving forward quickly vs being able to argue with-a-doubt the reasons a decision was made.
Get ‘em onboard. There are many team building exercises to help everyone understand the power of group thinking and quick decisions. One way is Leveraging a group for quick decisions, another is guessing the number of jelly-beans in a jar using the average of all guesses from a sizeable group that is surprisingly accurate.
Initially, to have T-Shirt sizing work smoothly, it’s my opinion you will need an experienced scrum master walk them through it – until they get going. Once they do, everyone should see the benefits.