One of the things that we emphasise in the Metrics Masterclass is the idea that XmR charts come built-in with a specific approach to improvement.
This two-prong recommendation seems simple. As I write this I can see you nodding your head (or rolling your eyes). But I’ve found that in practice, this set of recommendations produces something quite remarkable: it means that whenever you put a metric on an XmR chart, you know exactly what to do. There’s no longer any question about “so what?” or “what should I do about this?” — which so often happens when you’re looking at a wiggling chart in the context of a dashboard.
XmR charts were originally developed for and used in manufacturing. The goal in manufacturing is in some ways simple: make parts with consistently tight tolerances. In this domain, exceptional variation is bad — we don’t want gears with ratios that are ever so slightly off, nor do we want furniture that just barely fits together.
Consistency of fit and finish is so important, in fact, that you will often find videos of car reviewers examining inconsistent seams and slightly malformed joints as proof of bad build quality. (Tesla, in particular, comes to mind here — there are a gajillion videos of badly built Tesla cars on YouTube, and I watch a dozen of them every couple of years, for fun).