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Good QA/QC rests on a few statistical ideas, and most of them are simpler than they look. These articles and workbooks explain the methods behind the Geoscience Analytics apps, where they come from, and what they will and will not tell you about your laboratory.
The workbooks are ordinary Excel files with no macros. Every calculated number is a formula you can follow, and you can paste in your own results. They are free to download, with no sign-in.
If you read one thing, read The Impact of Geological Variation when Quality Controlling Precision. A field duplicate is not a duplicate, and it may not be the laboratory that is at fault.
Topics
Each topic brings together the articles, workbooks and app pages on the same subject.
| Title | Description |
|---|---|
| Control charts for standards | Shewhart, the Nelson rules and the two-sided CUSUM: what each chart catches, what it misses, and how to read them together. |
| Duplicates and precision | Paired results from field, coarse and pulp duplicates: fitting a line that bad pairs cannot pull, and measuring precision. |
Free Excel workbooks
| Title | Description |
|---|---|
| Change-point analysis workbook | Did the laboratory’s results shift, where, and how sure can you be? Taylor’s change-point analysis with a bootstrap confidence, on one standard’s results. |
| Repeated median regression workbook | A straight line through paired results that a few bad pairs cannot pull off course: Siegel’s repeated median, Theil-Sen and least squares side by side, with the AMC robust mean and SD. |
| Shewhart and CUSUM workbook | One standard on a Shewhart chart with the eight Nelson rules and on a two-sided CUSUM, side by side. Paste in your own results. |
Articles
Most first appeared on LinkedIn; each links back to the original.