Table 3.

Variance Component Estimate

Sample	Source of Variance	Relative Standard Deviation (%)
Control	Analyst-to-analyst	1
	Day-to-day within Analyst	1
	Instrument-to-instrument within daya	2
	Overall	3
70% of Target	Analyst-to-analyst	0
	Day-to-day within Analyst	0
	Instrument-to-instrument within daya	3
	Overall	3
85% of Target	Analyst-to-analyst	0
	Day-to-day within Analyst	1
	Instrument-to-instrument within daya	2
	Overall	3
100% of Target	Analyst-to-analyst	0
	Day-to-day within Analyst	2
	Instrument-to-instrument within daya	2
	Overall	3
115% of Target	Analyst-to-analyst	0
	Day-to-day within Analyst	1
	Instrument-to-instrument within daya	2
	Overall	2
130% of Target	Analyst-to-analyst	0
	Day-to-day within Analyst	2
	Instrument-to-instrument within daya	3
	Overall	4

The analysis was based on the data generated in the recovery study (Table 1) with three analysts, 2 instruments over 8 independent assays (one assay per day). Variance component analysis was performed to estimate the variance contributed by each factor.

^aInstrument-to-instrument variance contains the variance of sample preparation.