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What is Relative Sizing and how use it for Sprint Planning?

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The Fibonacci Sequence is commonly used in assigning story points. (Image credit:

Relative Sizing, a.k.a. Relative Estimation is a capacity planning tool to help Agile teams plan for their Sprints. It helps them establish how much work they are committing to, and ultimately reflects the cost of implementing a User Story or task.

What are Story Points and how are they used in estimation?

The full team reviews the Tasks or User Stories, typically during Sprint Planning, and collectively estimate the relative size of each item by agreeing on an appropriate value, known as Story Points.

There are so-called Planning poker tools that can assist with this process (google is your friend). They help neutralise a dominant team member from having a disproportionate influence on the exercise. These tools are commonly based on the Fibonacci sequence (1, 2, 3, 5, 8, 13 etc.) which helps to prevent estimates being too similar. The higher the number, the more complex the task or User Story, and the more effort required to complete it.

What are the benefits of Relative Sizing?

The benefits are that it helps avoid commonly experienced challenges with any form of time-based estimation, predominantly the quest for unrealistic accuracy (anyone familiar with annual budgeting can attest to this! Do they ever hit the mark!?).

Furthermore, it provides an opportunity for the whole team to provide input into how much work is committed to in a Sprint. This helps drive team engagement.

Importantly, it should never be used as a way to measure performance of a team, or worse between teams. There are many variables that impact the performance of a team. The ability to accurately size and complete work committed to, should not be one of them.

Are there other ways to estimate work?

There are other ways to estimate work, such as T-shirt Sizing where work is tagged as being a Small, Medium, Large, or Extra Large type of activity.

As part of helping teams understand relative sizing, I've run activities where I get them to estimate the effort involved with washing animals ranging from giraffes and lions to rabbits. Washing a rabbit is obviously easier than a giraffe, but how about a hungry lion vs a giraffe?

Is there scientific proof for relative sizing?

Interestingly, despite what many coaches might believe, there is no proven scientific evidence that relative sizing works. However, the logic behind seems to make sense, and it does feel more natural than thinking one can plan all work based on 'time' alone.

I used this and this as input to this post. You may find this of interest as well.


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