The who Multicentre Growth Reference Study: Planning, Study Design, and Methodology

TLDR

Rigorous training, standardization, and monitoring are essential to reduce random error and bias in multicenter studies. The study employed rigorous anthropometric protocols, including initial and bi‑monthly training, annual restandardization by WHO experts, paired independent measurements with repeat checks, robust equipment, and continuous central and local monitoring to ensure precision and accuracy. These procedures serve as a model for research settings.

Abstract

Thorough training, continuous standardization, and close monitoring of the adherence to measurement procedures during data collection are essential for minimizing random error and bias in multicenter studies. Rigorous anthropometry and data collection protocols were used in the WHO Multicentre Growth Reference Study to ensure high data quality. After the initial training and standardization, study teams participated in standardization sessions every two months for a continuous assessment of the precision and accuracy of their measurements. Once a year the teams were restandardized against the WHO lead anthropometrist, who observed their measurement techniques and retrained any deviating observers. Robust and precise equipment was selected and adapted for field use. The anthropometrists worked in pairs, taking measurements independently, and repeating measurements that exceeded preset maximum allowable differences. Ongoing central and local monitoring identified anthropometrists deviating from standard procedures, and immediate corrective action was taken. The procedures described in this paper are a model for research settings.