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.

Download the workbook (Excel, 140 KB)

Excel 2010 or later, or LibreOffice. No macros. Licence: CC BY 4.0, free to use and share with credit to Geoscience Analytics.

What it shows

The workbook plots one standard (CRM) on a Shewhart control chart, with the eight Nelson rules, and on a two-sided CUSUM chart, one above the other on the same run order. You can see, result by result, how each chart reacts to the same data.

The example data: 60 simulated results, 1 SD low from result 21 to 35 and 1 SD high from result 46. No result goes beyond 3 SD; the Nelson rules and both CUSUM totals find the two shifts.

The sheets

  • README: what the workbook does, every column explained, the eight Nelson rules, how to choose k and h, and the sources.
  • Calculator: the inputs at the top (yellow cells), then one row per result: the z score, the Shewhart status, each Nelson rule, C+, C− and the CUSUM signal. Every calculated number is a formula.
  • Charts: a summary of what the charts found, then the Shewhart chart and the CUSUM chart.

Using your own results

  1. On the Calculator sheet, set the target (certified value), the SD, k and h. Use the certified value and SD where the certificate gives them.
  2. Clear the example: select C10:C509 (and B10:B509 for the sample IDs) and press Delete.
  3. Paste the results for one standard and one element into column C from C10 down, in run order, with no gaps (Paste Special, Values). Up to 500 results.
  4. Read the Charts sheet. Both charts resize to the number of results.

Learn more