Derivation
variable: waisc (table[s]: css_sei)
variable: waist_op1 (table[s]: gap_combined)
variable: waist (table[s]: ncd_combined)
variable: waiscf/waiscs (table[s]: sts_fup, sts_stsf, sts_stsp, arkk_arkq, kduk_kduq, phdk_phdq)
Waist circumference from ARK, STS, KDU and PHD were collected twice so average of the 2 readings is calculated. All waist circumference variables from the various tables are in cm so if necessary are renamed to waisc