Table 3. Ranges of Hb concentrations and mean μ_s’ (averaged over 350-600 nm) for Phantom Sets 2 and 3. Set 2 had two µ_s’ levels, each of which had the same range of Hb.

	Instrument 1 ranges		Instrument 2 ranges
	[Hb] (µM)	Mean µs’ (cm-1)	[Hb] (µM)	Mean µs’ (cm-1)
Set 2: µs’ level 1 (n=4)	6.4-14.3	14.0-13.0	7.3-16.2	14.3-13.1
Set 2: µs’ level 2 (n=4)		23.4-21.7		23.9-21.9
Set 3	5.9-35.2	23.6-17.3	5.0-50.0	27.8-17.0