Fig. 2From: Reference values of impulse oscillometry (IOS) for healthy Chinese children aged 4–17 yearsPearson’s correlation for resistance at 5 Hz, resistance at 20 Hz, reactance at 5 Hz, impedance at 5 Hz, resonant frequency, and reactance curve area below zero for boys and girls. R5 = resistance at 5 Hz, R20 = resistance at 20 Hz, X5 = reactance at 5 Hz, Fres = resonant frequency, Z5 = impedance at 5 Hz, R5–R20 = fall in resistance between R5 and R20Back to article page