Fig. 2From: Validity of accuracy and trending ability of non-invasive continuous total hemoglobin measurement in complex spine surgery: a prospective cohort studyBland-Altman analysis plots for SpHb and tHb. This plot shows mean bias and limits of agreement (±1.96 standard deviation) with the percentage error (%) and the number of out of limits of agreement. a 200 data pairs with perfusion index values ≥1.0 group. b 72 data pairs with perfusion index values < 1.0 groupBack to article page