Agile Story Point Estimation Techniques - T-Shirt Sizing

In my previous articles, we have discussed Agile Story Point Estimation and Agile Story Point Estimation Techniques - Planning Poker. In this article, we will learn Story Point Estimation using T-Shirt Size Technique.

What is T-shirt sizing?

T-shirt Sizing is one of the Story points sizing technique to estimate user story usually used in agile projects. It's a relative Estimation Technique.

Rather than using a number of planning pokers, here, Items are classified into t-shirt sizes: XS, S, M, L, XL.

The term originates from the way T-shirt sizes are indicated in the US. Rather than having T-shirts in sizes 4, 5, 6 etc, there are just a few sizes: Small (S), Medium (M), Large (L) and Extra Large (XL) and so on.

With T-shirt measuring, the development team is made a request to evaluate whether they think a story is extra-small, small, medium, large, extra-large, or double extra-large. By expelling the numerical score, the development team is allowed to think in a more dynamic manner about the exertion associated with a story. The sizes can, if necessary, be given numerical value after the estimation is finished.

 
Image Source: http://www.deltamatrix.com/agile-estimation/

Steps
  1. Make S, M, L, XL Cards
  2. Product Owner will explain the story to be estimated and the development team will ask questions if they have any issues or unclarity. For example,

    Design Related- Do we have to learn new things before starting the design/HTML/jQuery etc?
    Coding Related- Do we have any code class library ready or we have to write it from the scratch?
    Testing Related- Any specific setup required for Unit testing?

  3. Each developer gives each story a t-shirt size.
  4. All in Development team will raise their cards simultaneously.
  5. The development team will discuss the differences.
  6. The product owner explains the story further or clarifies misunderstanding if any.
  7. The team will Go back to Step 3-Step5 until all are agree with one size.
  8. Complete or place the stories in size buckets.
  9. Estimate the time to complete all stories in S, M, L, XL buckets.

     
    Image source :https://www.slideshare.net/agiledad/agile-estimating-planning 
Benefits
  • This is a very informal strategy and can be utilized quickly with a large number of items.
  • It is a popular agile relative estimation technique.
  • Forcing the estimate into one of a fixed set of sizes allows the process to go quickly
  • It is a good way to Introduce terms to relative estimating.
  • It is very effective for affinity estimating
T-shirt sizes can be a great way to becoming familiar with relative estimating. So, start with them if your dev team finds that easier.
But However, insignificantly put some fundamental numbers on them (e.g., Medium=5) and after that steadily shift to using the numbers directly.

I hope you like this article. stay tuned for more article on Agile Development. If you have any query, please feel free to post in the comments section. 

Reference 
  • http://www.deltamatrix.com/agile-estimation/ 
  • https://www.mountaingoatsoftware.com/blog/estimating-with-tee-shirt-sizes
  • https://blogs.msdn.microsoft.com/oldnewthing/20090512-00/?p=18293
  • https://www.slideshare.net/agiledad/agile-estimating-planning