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PRACTICAL QC

PRACTICAL QC. M.Jabari 2005. Quality assurance. « Do what you have written and write what you have done ». LEVEY-JENNINGS CONTROL CHART. It is generally useful first to try to classify the error as random or systematic. WESTGARD RULES. The set of rules recommended by westgard (1981 ).

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PRACTICAL QC

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  1. PRACTICAL QC M.Jabari 2005

  2. Quality assurance « Do what you have written and write what you have done »

  3. LEVEY-JENNINGS CONTROL CHART It is generally useful first to try to classify the error as random or systematic .

  4. WESTGARD RULES The set of rules recommended by westgard (1981 ) .

  5. WESTGARD RULES 1:2S : one observation in the warning zone (Outside 2S)

  6. WESTGARD RULES 1:3S : one observation in the rejection zone (Outside 3S)

  7. WESTGARD RULES 2:2S : two consecutive control observations in the warning zone, on the same side of the mean (Outside 2S)

  8. WESTGARD RULES R:4S : two consecutive control observations in the warning zone. ( The range of two results is greater than 4 SD)

  9. WESTGARD RULES 4:1S : Four consecutive results outside 1SD on the same side of the mean.

  10. WESTGARD RULES 10M : 10 consecutive observations on the same side of the mean

  11. LOGIC DIAGRAM CONTROL DATA NO 1:2s IN-CONTROL ACCEPT RUN YES NO NO NO NO NO 1:3s 2:2s R:4s 4:1s 10 X YES YES YES YES YES OUT-OF-CONTROL REJECT RUN

  12. CUSUM TECHNIQUES When a systematic error is present , the cusum values will steadily increase . The slope of the line will be related to the size of the systematic error .

  13. CUSUM TECHNIQUES Cusum techniques generally provide better detection of systematic errors than levey-jennings charts.

  14. S (X-M) = -10 2 S (X-M) = 44 S(X-M)2 SD = n-1 44 SD = 19 SD = 1.7

  15. LEVEY-JENNINGS CHART +3SD +2SD +1SD -1SD -2SD -3SD

  16. CUMULATIVE SUM CHART +2SD +1SD -1SD -2SD -3SD -10 SD

  17. Patients mean Accuracy control Recovery Linearity

  18. RECOVERY Glucose: Specimen 1 : 150 mg% Specimen 2 : 100 mg% Add together Expected value : 250 mg% Observed value : 230 mg%

  19. RECOVERY 250 - 230 = 8 X100 % Bias = 250 % Recovery = 100 - 8 = 92% Ideal recovery is greater than 95%

  20. LINEARITY In this method mixed two specimen with different ( one high and other low) concentration ,and reassay . The chart of concentration and absorbaance must be strightforward .

  21. Good area < 1s 1s < warning area < 2s rejection area > 2s

  22. CV is changing The dispersion is increased (CV 2, CV 3) Accurate but not precise Not systematic

  23. Mean is changing The dispersion is the same The target is moving Precise but not accurate Systematic

  24. Both are changing Not accurate and not precise … Systematic &non Systematic bias …

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