Why do we use Fibonacci Numbers to estimate in Scrum?

Shape Image One
Why do we use Fibonacci Numbers to estimate in Scrum?

One of the core values of Agile is that “We value individuals and their interactions over tools and process”.  Meaning that in an environment where requirements and technology are rapidly changing, we want people to communicate directly with each other to reduce the latency of decision making. The reliance on tools and processes may not only delay the decision-making but also distort the information being relayed.

Fibonacci Numbers

Fibonacci Numbers are the addition of the previous 2 numbers (1,2,3,5,8,13,21…). Fibonacci Numbers were first described in Indian Mathematics in 200BC by Acharya Pingala, which was made popular in western mathematics by Leonardo Bonacci.

Why use Fibonacci Numbers in Estimation

Fibonacci Numbers is a nonlinear progression (the gap between adjacent numbers keeps increasing exponentially) This increased gap in numerical value forces a deeper discussion between the team members before they all agree to assign the appropriate Fibonacci Number associated with the complexity of the work.

The assigning of Fibonacci numbers to a product backlog item (PBI) is done by leveraging the Delphi Wideband Estimation technique (group consensus-based estimation). When used in tandem Fibonacci number and Delphi Wideband Estimation helps the team in the following ways:

  • Deeper discussion between the team members to understand the complexity of the work
  • Cross-functional discussion on what would be required to deliver the PBI i.e., coding, integration, and testing are discussions rather than fragmented estimation
  • This ongoing discussion helps the team leverage the osmotic process of learning about the requirements rather than the waterfall environment where each role was defined and siloed.
  • Understanding of the requirement and the technical solution information is well understood between all team members, hence eliminating the island of expertise within the team. 

When used properly estimating with Fibonacci numbers in conjunction with Delphi Wideband Estimation is a powerful set of tools for the teams to understand, solution and estimate the anticipated work.

Leave a Reply

Your email address will not be published. Required fields are marked *