Fig. 5. Bland-Altman plots for systolic, diastolic, mean, and pulse pressure; each with data of 50 patients. Individual averages ± SDs of the pressure ranges (x-axis) and errors (y-axis). Drawn lines  are averages and dashed lines  indicate ± SD and ± 2 SD (SD determined over the individual patient averages). Both the x-axis and y-axis have the same scale. Note that the x-axis of the systolic pressure runs from 50 to 200 mmHg. The SDs in parallel to the x-axis (showing the individual variability in blood pressure) are larger than the 1 s parallel to the y-axis (showing the individual variability in the difference between noninvasive and invasive arterial pressure). This indicates that over a wide range of pressure levels invasive and noninvasive pressures give comparable values.