$f_R$	Respiratory rate
bpm	breaths/min
OSA	Obstructive sleep apnea
ROI	Region of interest
px	Pixel
x${}_C$	Location on x axis of the ROI’s central point
y${}_C$	Location on y axis of the ROI’s central point
FO	Optical flow
PCA	Principal component analysis
ICA	Independent component analysis
UB	Upper body
HS	Horn and Shunk
BH3	Bioharness
th	Threshold
f${}_{occ}$	Percentage occurrence frequency
MOD	Mean of differences
LOA	Limit of agreement
sd	Standard deviation