Bland-Altman analysis of blood flow in the lower abdomen for repeated measurements. Bland-Altman analysis revealed no systematic bias (fixed bias or proportional bias) between two measurements. The difference (y-axis) and mean (x-axis) in blood flow in lower abdomen (Ab) between two measurements over three different days. Results are based on 180 samplings (comparison between 1st and 2nd, 2nd and 3rd, and 3rd and 1st measurements) in 60 participants. The solid line indicates bias and the dashed lines are the limits of agreement of ± 1.96 SD (± 2 SD on the figure). The open circles correspond to 1st vs. 2nd measurement. The grey circles correspond to 2nd vs. 3rd measurement. The closed circles correspond to 3rd vs. 1st measurement. Material reproduced, with data added to the figure adapted from Osada et al. , with permission from IOP Publishing Ltd.