Pareto Analysis of Blocked Cards

The role of metrics in TPS is crisply explained in Jeffery Liker’s book “The Toyota Way”. He explains that Toyota prefers simple metrics and does not use many of them at the plant or the company level. Some of my peers may be surprised to hear this!

The author highlights his point with a simple example. During one of his visits to one of the Toyota plants, he was told that apart from a few basic metrics (like cost of plant operations, parts per million defects, some safety related and productivity), the metric Toyota finds most useful as a manager is the number of “Andon” pulls made by each Team Member to stop the production line. They regularly graph this data, noting the problems that caused the Andon pulls and use Pareto Analysis to identify the most common reasons. They take corrective measures to address these reasons. The VP of this manufacturing unit explains how “this metric provided great insight into the actual day-to-day problems faced in the production process”.

The analogy to this in software systems that use the Kanban Method, is the blocked card. Most of us who have been working using the Kanban Method have experienced that blocked cards are a big impediment to smooth flow, increasing WIP counts and cards getting stale.

If you have a physical board, it would be difficult to track this manually over time. We, in SwiftKanban (www.SwiftKanban.com), have built functionality to track this, though I would personally prefer a two level categorization.

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However, not all tool providers have done even this. So, the question is: are you doing an analysis of the reasons for having Blocked Cards in your Value Stream during your retrospectives? Are you putting a corrective action for the same? I suspect that teams are missing a significant potential for continuous improvement by not doing a Pareto Analysis of Blocked Cards.

I would like to hear from the practitioners how frequently they are doing Pareto Analysis of blocked cards and then defining action items during a retrospective to fix them. If you have a physical board, are you doing it manually? Look forward to your response…

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