Data-Collection and Management Practices for Reducing Errors for Height, Weight, and BMI

Equipment and space
 Choose appropriate equipment
 Check and calibrate equipment regularly
 Keep extra batteries for scales
 Provide a private area for child measurements, if possible
Measurement protocols
 Chose a protocol that matches that used in the growth charts
 Have written copies of measurement protocols available for review
 Train and standardize data collectors
 Make sure data are recorded in the appropriate units (eg, kilograms, pounds)
 Make sure data are measured and recorded to the nearest unit specified in the protocol (eg, 0.1 cm for height, 0.1 kg for weight)
 Collect some replicate measurements for assessment of reliability, if feasible
 Use as few observers as is feasible to take measurements, especially for research studies
 Identify observers on data-collection forms or data-entry programs
Data management
 Use as exact ages as possible
 Have unique identifiers for children
 Calculate BMI, percentiles, and z scores by using tables or computer programs