Table 4.

Repeatability and Within‐Laboratory Imprecision for Three Levels of Quality Controls of 25‐OH Vitamin D2 and D3

	25‐OH Vitamin D2			25‐OH Vitamin D3
Mean (ng/mL)	13.8	40.8	99.9	11.0	24.8	61.5
Repeatability CV	4.4	3.2	2.8	4.4	4.1	3.4
Within‐laboratory CV	5.7	4.6	3.7	5.7	5.7	5.1

Repeatability (formerly called within‐run imprecision) was calculated by taking the average of variances of replicates from different days, and within‐laboratory imprecision was calculated from repeatability and variances of daily means as described in Clinical Laboratory Standards Institute (CLSI) EP15 A2 guidelines 31.