Figure 2.

Plot of data collected from 10 volunteers during a “breathe down test” (see Methods). Each point on the plot represents one pair of a phone reading and Masimo Radical 7 reading. The root-mean-square deviation of bias between the two instruments in this test was 2.2 oxygen saturation counts. The upper and lower limits of agreement per Bland and Altman²⁰ are shown as dashed lines. A second-order polynomial fit of the data is shown as a solid line. Spo₂ = oxygen saturation.