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

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

Modified shewhart control charts for use with multi-rules

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

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

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

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

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

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

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

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

3SD 2SD 1SD M -1SD -2SD -3SD 3SD 2SD 1SD M -1SD -2SD -3SD

Answers for activity Day 21, 22, 24, 26, 27, 30, 31, 33, 34, 36-44 – in control Day 23, 28, 29 – 12s Day 25 - 13s Day 32 – 22s Day 35 - R4s Results of activity- verify 14

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