Compute the average CV over the 10 subjects as an overall measure of variability of the assay. In general, a CV of <10% is considered excellent, ‰¥10% and <20% is considered good, ‰¥20% and <30% is considered fair, and ‰¥30% is considered poor.

How would you characterize the reliability of the APC assay based on these criteria? 

Cardiovascular Disease
Activated-protein-C (APC) resistance is a serum marker that has been associated with thrombosis (the formation of blood clots often leading to heart attacks) among adults. A study assessed this risk factor among adolescents. To assess the reproducibility of the assay, a split-sample technique was used in which a blood sample was provided by 10 people; each sample was split into two aliquots (sub-samples), and each aliquot was assessed separately. Table 2.19 gives the results.

Table 2.19: APC resistance split-samples data

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Sample number A A-B 2.22 1.88 0.34 3.42 3.59 -0.17 3 3.68 3.01 0.67 0.27 2.64 2.37 0.42 2.68 2.26 3.29 3.04 0.25 0.28 3.85 3.57 2.24 2.29 -0.05 3.25 3.39 -0.14 10 3.30 3.16 0.14