Fig. 7.

Flow errors produced by syringe potentiometer (SP), weighted averaging (WA), and polynomial least-squares (PolyLS) calibration methods as a function of increasing numbers of calibration strokes. Values are presented as means ± 95th percentile confidence interval. The gray shaded region denotes the ±5.0% error margin of volume errors as recommended by the American Thoracic Society (ATS) and the European Respiratory Society (ERS) (11). Note that flow errors produced by the SP method fall within the ATS/ERS-recommended error margin across all ranges of flow rates after only 5 calibration strokes.