1. Modified shewhart control charts for use with multi-rules

2. Westgard Multi-rules 12S rule 13S rule 22S rule R4S rule 41S rule
10X rule
8-5 2

3. Westgard Multi-rules, 12S Rule
One of two control results falls outside ±2s
Warning Rule – does not cause rejection of a run
Alerts technologist to possible method or instrument malfunction

4. Westgard Multi-rules, 13s Rule
When the control limits are set as the mean ± 3s
A run is rejected when a single control measurement exceeds the mean plus 3s or the mean minus 3s control limit

5. Westgard Multi-rules, 22S Rule
22s - reject when 2 consecutive control measurements exceed the same mean plus 2s or the same mean minus 2s control limit
Level 1
Level 2

6. Westgard Multi-rules, R4S Rule
R4s- reject when 1 control measurement in a group exceeds the mean plus 2s and another exceeds the mean minus 2s
Level 1
Level 2

7. Westgard Multi-rules, 41S Rule
41s- reject when 4 consecutive control measurements exceed the same mean plus 1s or the same mean minus 1s control limit
Level 1
Level 2

8. Westgard Multi-rules, 10x Rule
10x- reject when 10 consecutive control measurements fall on one side of the mean
Level 1
Level 2