I’ve been using Extreme Programming Planning Poker since James Grenning showed it to me in 2003. Much has been written about it, how to use it, and how it quickly leads to estimates as good as any other more detailed and time-consuming techniques.
I like it when something I use works. I like it even more when I can point to nature or science for the underlying principles of why it works. The sequence of numbers that planning poker is based on came from the Fibonacci set:
“By definition, the first two Fibonacci numbers are 0 and 1, and each subsequent number is the sum of the previous two. Some sources omit the initial 0, instead beginning the sequence with two 1s.
In mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relation
Fn = Fn-1 + Fn-2 with seed values F0 = 0 and F1 = 1
This ties back to nature, such as the relative size between the whorls in a nautilus shell, and the golden ratio derived from the summation of the inverse of the set:
So, faithful to nature, I’ve been using decks of planning poker cards with the numbers 1, 2, 3, 5, 8, 13, 21, 34, 55 …, depending on the size of the product backlog.
Imagine my surprise when I was called by a very distressed Dr. Stephen Hawking, the theoretical physicist. He was inquiring about who was “screwing around” with the Fibonacci sequence. He and his fellows had been noticing a spate of distressing phemona lately, such as:
- The speed of light starting to vary unpredictably.
- Objects falling from trees at varying velocities that were independent of any known attributes.
- Nautilus shells spontaneously bursting apart.
- Other worrisome perturbances of the natural order.
They had studied the problem, and tracked its origins back to us, the agile community of software developers. They found that a number of us were perverting the Fibonacci sequence. They found a number of decks of cards and posters that showed the following sequence:
Dr. Hawking indicated a high degree of probability that there was a correlation between the abnormal change in natural phenomena and this perversion of the Fibonacci sequence.
Dr. Hawking pleads, and I support, that we cease and desist from our misuse of the Fibonacci sequence, and return to the real sequence. This will reaffirm our relationship with nature and our world.
Thanks for your support.