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As part of the WADA (World Anti Doping Agency) accreditation process a standard

ID: 267330 • Letter: A

Question

As part of the WADA (World Anti Doping Agency) accreditation process a standard sample of human urine containing 42.0 ngmL-1 of Iwas sent to five laboratories. The laboratories (labelled A - E below) were asked to carry out six determinations of the clenbuterol concentration and obtained the following results (ngmL-1) 42.1 42.1 41.941.142.2 40.1 42.541.6 39.8 43.542.843.8 43. 42.743.3 35.0 42.2 43.6 43.9 41.9 43.037.1 41.6 42.2 39.0 40.536.8 42.0 41.8 42.6 Using appropriate statistical calculations discuss the accuracy and precision of the five laboratories

Explanation / Answer

Answer:

Based on the given data:

Accuracy Calculations:

Accuracy can be determined in terms of % Error in measurement as compared to reference standard value.

% Error = | (Theoertical value - Experimental value / Theoretical value) | *100

% Error for all five laboratories value was calculated as below:

Therefore, measurements obtained from Lab A and Lab B are more accurate as compared to other labs. For Lab D the values obtained for clenbutarol are least accurate with a % error of 6.90%.

Precision Calculations:

Precision is measured in terms of variability in measurement of replicates. It is calculated as below:

Covariance (%CV) = (Standard deviation / Average)*100

Based on the %CV values, the results of Lab C are most robust and repeatable (%CV 0.96%), whereas Lab D has highest variability in replicate measurements ( %CV 8.32%).

Laboratory Clenbuterol values ng/ml Mean A 42.50 41.60 42.10 41.90 41.10 42.20 41.90 B 39.80 43.60 42.10 40.10 43.90 41.90 41.90 C 43.50 42.80 43.80 43.20 42.70 43.30 43.22 D 35.00 43.00 37.10 40.50 36.80 42.20 39.10 E 42.20 41.60 42.00 41.80 42.60 39.00 41.53