Flow Efficiency

A few years ago now I saw David Anderson giving a talk titled How Deep is Your Kanban?. The concept of measuring the depth of a Kanban system is one I have found useful since that point. It in itself is a useful feedback loop and can be used to capture the journey that a team has undergone. I have also gained value from it to help identify areas to improve and even as inspiration for potential changes that could be made.

However an element of the Deep Kanban model served as an area of confusion to me. Specifically using Flow Efficiency as a means of managing flow. I wasn’t sure how to use this or indeed how to calculate it. In 2013 I reached out to David and some other members of the Kanban community for guidance.
A Twitter Dialogue with David Anderson and Mike Burrows
Sadly this left me none the wiser. I left Flow Efficiency alone and moved on to other things. However recently I’ve been reading Daniel Vacanti’s brilliant book Actionable Agile Metrics for Predictability. Within the book Daniel defines flow efficiency as

“… the ratio of the total elapsed time that an item was actively worked on to the total elapsed time that it took for an item to complete(it’s total Cycle Time).”

This gives a useful measure of how efficient the system is and through acting upon this measure we can dramatically reduce the average cycle time.