Note: In his book “Actionable Agile Metrics for Predictability”, my colleague Dan Vacanti expands on my FedEx example while discussing further the notion and benefits of “slack” in the software development context. You’ll find this discussion in Ch. 13 Pull Policies.

“The beauty of using a flow system and a visual control is that we can measure cycle time and we can observe context…

The trappings of false certainty we gave ourselves in previous methodologies are being replaced with the comfort of graspable variation in kanban…

We now see knowledge work for what it is – a chaotic system that is fully manageable and understandable by its outputs and contexts, but very much unknowable by its actions and specifics.”

– Jim Benson, Sep 2011

The title of this post contains an answer and a question. However, it’s a “question” that prompted the answer part of this title, and my recollection of how both came to me originally, that I’m interested in sharing in this post and hope you find interesting if not amusing. As for providing an “answer” to the question part of this post’s title, that I’ll leave entirely to you.

Who Mentioned Variability?

This summer I had an opportunity to help out with a training class introducing the kanban method to a few members from several teams that all worked in a software development and operations support context. On the second day of this training we came to a section titled “Understanding Variability.” As the class began discussing why this might be important, I couldn’t help but flashback to a time when I heard my wife shout “It’s Slack! Who can’t see that?”, as she was watching a TV program in our family room. I’m sure at the moment of my flashback, more than a few in the training classroom wondered how I could be enjoying the discussion so much, while I sat there listening with a big smile on my face, chuckling a bit, as if I was somewhere else hearing a comic telling his latest and greatest jokes. The truth was, I was somewhere else for the moment.

The year 2009 was coming to an end, and it was a few days before New Year’s Eve. I was at home in the loft sitting at my computer reading or writing something, when I heard my wife shout from below “It’s slack! Who can’t see that?” as she walked out of the family room. The tone in her voice hinted it was the “Who can’t see that?” part that she was most excited and proud to share right at that instant. However, I was much more interested in knowing the yet unknown question that prompted her to excitedly shout “It’s slack!” It was obvious too, she had more to share with me right then, something I’ll now share a bit about with you. (continue reading…)