Q: 1 level is out 3 sd, but the other 2 levels are "in", what do we do?

"We have a 1:3s rule to reject on one level, but 2 other levels are within 1 SD. Staff is just repeating the 1:3s. Is that the right approach? Also, do you apply rules across materials?"

[Another question from the Cut Your QC webinar, now available as an on-demand recording:

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I'm going to assume this question is describing a single incident, where one level exceeds the 1:3s and the other two levels are acceptable. If there is a 1:3s violation, that's a significant outlier - even for a Six Sigma method - and the laboratory should treat it was a real error, not a false rejection. Repeating a 1:3s to get it to fall back "in" is an extended Gambler approach to QC. Highly discouraged. But not surprising that once staff gets used to repeating controls outside 2 SD, they start repeating after every outlier.

The last part of the question is a more basic question about Westgard Rules interpretation. You can interpret the Westgard Rules across levels/materials and across runs. Every interpretation like this gives you another chance to catch an error, so implementing all of those angles is beneficial. The only obstacle may be the software you are using – it may not implement every interpretation, and the software might not explicitly detail whether or not it does so. Try to get as much detail from your software vendor as possible to see what's possible.