1. Quality Control (2) Lecture 6
Quality Assurance
Quality Control (2)
Lecture 6

2. Westgard Multi-rule Analysis
Two levels of control at different concentrations will be more efficient in monitoring the method when evaluated statistically
By running and evaluating the results of two controls together, trends and shifts can be detected much earlier
Westgard and associates have formulated a series of so called “multi-rules” to help evaluate results from Gaussian distribution both within a level of control and between control levels

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

4. Used when 2 levels of control material are analyzed per run
Westgard Multi-rules
12S rule
13S rule
22S rule
R4S rule
41S rule
10X rule
Used when 2 levels of control material are analyzed per run
8-5 4

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

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

7. 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

8. 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

9. 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

10. Westgard Multi-rules, 12S Rule
10x- reject when 10 consecutive control measurements fall on one side of the mean

12. Random or Systematic 13S and R4S usually associated with random error
22S, 41S, and 10X most often associated with systematic errors

13. 3SD
2SD
1SD M
-1SD
-2SD
-3SD
3SD
2SD
1SD M
-1SD
-2SD
-3SD

14. Answers for activity
Day 21, 22, 24, 26, 27, 30, 31, 33, 34, – in control
Day 23, 28, 29 – 12s
Day s
Day 32 – 22s
Day 35 - R4s
Results of activity- verify 14

15. Use of Patient Samples as Controls
Using of patient samples for quality control is acceptable because:
The physical and chemical differences between control material and patient samples are absent
The data being generated by the analysis of the patient samples require no extra effort to obtain for use as quality control data
Inexpensive method of quality control