ALT Crosschecking these two measures over 1,067 data points, the team found a clear pattern of errors. For nonwhite people the machines mostly tended to overestimate saturation levels by several points. The study only included participants who identified as Black or white, but the authors noted that degrees of errors have also been observed among Latinx, Indigenous, and many other nonwhite people. The team’s follow-up study, published in 2007, focused on safety errors for people with “intermediate” skin tones and included a larger group of women. This more detailed data again found a clear pattern: pulse ox “bias was generally the greatest in dark-skinned subjects, intermediate for intermediate skin tones, and least for lightly pigmented individuals.” Racial errors grew significant at lower oxygen levels, starting around 90 and growing widest in the 70s.