“…"Self-report" (29) is the primary way for pain measurement. There are various scales such as Verbal Rating Scales (VRS) (30), Numerical rating scales (NRS) (31), Visual Analog Scales (VAS) (32), Smiley-based Wong-Baker Scale (WBS) (33), Faces Pain Scales-Revised (FPS-R) (34) are used to get the selfreports from the chronic pain patients (35)(36)(37)(38). The second way of measuring pain is the "Observe behavior and infer" method (39).…”