T-shirt Size Method for Scrum Planning

Today I conducted my first scrum workshop. While preparing for that workshop, I realized that the single biggest mistake I have seen made most of the time is that when people use Fibonacci series to measure story points they confuse these relative estimates with the actual ones. When you see a number 3 its hard not to relate it to 3 hours or 3 days in our heads. It is unconsciously done by our minds. The same reason people take longer to read the color blue if it is written in red.

In order to avoid this from happening, I came up with t-shirt size method to estimate user stories. Using t-shirt sizes instead of number is ideal because story points in scrum are relative. Fibonacci series is a great choice for that but since these are numbers back of our mind we invariably relate them to actual estimates in hours or days. With t-shirt sizes that would not happen and you are able to compare the stories relatively quite easily. At the same time there is a catch. With Fibonacci you can easily calculate the story points and this makes it easier to plot the burnt down chart and measure your velocity. Now the question arises: Can we have the best of both worlds? Sure we can. By creating these simple cards as shown below you can do that easily. In these cards each t-shirt size is related to a Fibonacci number. When you are estimating, you forget the number and focus on the t-size. Once estimates are done, you can record the Fibonacci number on the card as your story points.

These cards are simple to create and makes planning a fun activity. Also by using t-shirt sizes when you are discussing stories during your sprint planning, this simple technique eliminates any pitfall of seeing the relative estimates as actual ones.

Feel free to comment and let me know what do you think about this approach.