Precision, Accuracy, and Two Quality Questions

Unpacking a conversation between John Willis and Bill Bellows on Taguchi's approach to quality

John Willis had Bill Bellows as a guest on the Profound podcast. Their conversation centered around Bill’s experience with Deming and Genichi Taguchi’s contributions to quality management. Here’s a link to part one and part two.

Their conversation introduced me to Taguchi’s methods, but that’s not the interesting point. The interesting point is how their conversation got lost in discussing precision versus accuracy, the “two questions of quality”, and statistical process control.

How many of darts are accurate? What’s the precisions on each throw?

John and Bill struggled to find mutual understanding. Their mental models collided over the dart board example and Deming’s red bead experiment. Their struggle is worth unpacking because there’s important information at the center. So, in this post, I’ll unpack their conversation to find the valuable center.