Fibonacci Must Die!

This content is syndicated from Practical Agility by Dave Rooney. To view the original post in full, click here.

Leonardo Fibonacci died over 760 years ago but he had a profound effect on mathematics in western civilization.  He brought what he had learned from mathematician in north Africa back to Europe and authored the book Liber Abaci, which described such things as the Hindu-Arabic numeral system and place value of numbers.  In the book he also showed how a number of mathematical problems were solved

3 Responses to “Fibonacci Must Die!”

  1. Kelly Waters says:

    Hi Dave. I read your post with interest. As you said, Fibonacci died a long time ago! :)

    Personally I really like Fibonacci numbers for estimating. I love the fact that the numbers get increasingly less accurate as the estimates get bigger. That just makes sense to me.

    But I agree with you that the range needn’t be that big. Remembering that the estimates are meant to be relative to each other – in other words a 3 is meant to be 3 times the size of a 1 – even just using 1, 2 and 3 is a pretty big range as it is, since work is meant to be broken down into small pieces.

    I think I agree with all your points except the headline and the last point that Fibonacci must die in agile teams. Instead I think it’s very useful, but the number range should be severely limited, perhaps to 1, 2, 3, 5, too big. How can we really talk about something that is 13 times bigger than something else. It’s hard to do that with any degree of accuracy.

    I also quite like the variation of 1, 2, 4, 8. Obviously this isn’t Fibonacci but does have an exponential shape to it which has the same positive effect on estimating accuracy as Fibonacci.


  2. Chris Davies says:

    I disagree, I’m afraid and for one reason only – project or Release planning.

    I have found it useful to estimate stories in the 13, 20 and 40 point range purely to understand the total story point count. Dividing velocity into this number gives the number of timeboxed iterations needed.
    Yes, if all stories were the same size we wouldn’t need to estimate at all and in some environments (ongoing product development as opposed to new projects) that is the ideal. Most of our projects, however, are of 4 – 9 month duration and we need to understand the full scope and whether we have a chance of delivering it. In this environment, it is impractical – and unnecessary – to break down all stories to the 1 – 3 point range up front.

    I am encouraging teams to break the story down to 5 points or less when planning each timebox. Until then, they can stay larger than that.

  3. Kelly Waters says:

    That’s a fair point Chris, if you are estimating an entire product backlog in points at the start of a big project, you may well have epics just as placeholders and they may well be larger until it’s time to break them down into smaller stories…


Leave a Reply

What is 1 + 9 ?
Please leave these two fields as-is:
Please do this simple sum so I know you are human:)

There are 101 ways to approach anything.
To find the best way, sometimes you need expert help

What People Say

“Kelly revolutionised the way our digital department operated. A true advocate of agile principles, he quickly improved internal communication within our teams and our internal clients by aligning our business and creating a much enhanced sense of transparency in the decisions the business was making. Kelly also introduced a higher sense of empowerment to the development teams...”


“Kelly’s a leading program director with the ability to take charge from day one and keep strong momentum at both a program and project level driving prioritisation, resourcing and budgeting agendas. Kelly operates with an easy-going style and possesses a strong facilitation skill set. From my 5 months experience working with Kelly, I would recommend Kelly to program manage large scale, complex, cross company change programs both from a business and IT perspective.”


“Kelly is an extremely talented and visionary leader. As such he manages to inspire all around him to achieve their best. He is passionate about agile and has a wealth of experience to bring to bear in this area. If you're 'lucky' he might even tell you all about his agile blog. Above all this, Kelly is great fun to work with. He is always relaxed and never gets stressed - and trust me, he had plenty of opportunity here! If you get the chance to work with Kelly, don't pass it up.”


“Kelly is an Agile heavy-weight. He came in to assess my multi-million $ Agile development program which wasn’t delivering the right throughput. He interviewed most of the team and made some key recommendations that, when implemented, showed immediate results. I couldn’t ask for more than that except he’s a really nice guy as well.”


“Kelly and I worked together on a very large project trying to secure a new Insurer client. Kelly had fantastic commercial awareness as well as his technical expertise. Without him I would never had secured this client so I owe a lot to him. He is also a really great guy!”


“Kelly came to the department and has really made a huge impact on how the department communicates, collaborates and generally gets things done. We were already developing in an agile way, but Kelly has brought us even more into alignment with agile and scrum best practices, being eager to share information and willing to work with us to change our processes rather than dictate how things must be done. He is highly knowledgable about agile development (as his active blog proves) but his blog won't show what a friendly and knowledgeable guy he is. I highly recommend Kelly to anyone looking for a CTO or a seminar on agile/scrum practices - you won't be disappointed!”


“Kelly was a great colleague to work with - highly competent, trustworthy and generally a nice bloke.”


“Kelly was engaged as a Program Director on a complex business and technology transformation program for Suncorp Commercial Insurance. Kelly drew on his key capabilities and depth of experience to bring together disparate parties in a harmonised way, ensuring the initiate and concept phases of the program were understood and well formulated. Excellent outcome in a very short time frame. ”


“I worked with Kelly on many projects at IPC and I was always impressed with his approach to all of them, always ensuring the most commercially viable route was taken. He is great at managing relationships and it was always a pleasure working with him.”


“I worked with Kelly whilst at Thoughtworks and found him to be a most inspiring individual, his common-sense approach coupled with a deep understanding of Agile and business makes him an invaluable asset to any organisation. I can't recommend Kelly enough.”


“Kelly was a brilliant CTO and a great support to me in the time we worked together. I owe Kelly a great deal in terms of direction and how to get things done under sometimes difficult circumstances. Thanks Kelly.”