1) This indicator relies on accurate age assessment. Since people often do not remember the exact dates of their children’s birth, the data collectors should always verify the child’s age. This can be done by reviewing the child’s birth certificate, vaccination card or another document; however, since many caregivers do not have such documents (and since they can include mistakes), it is essential that your data collectors are able to verify the child’s age by using local events calendars. Read FAO’s Guidelines (see below) to learn how to prepare local events calendars and how to train data collectors in their correct use.
2) Compared to measuring weight for height (showing wasting) and height for age (showing stunting), this indicator provides less useful data (as it is less clear what problem it represents). It is a composite indicator which combines chronic and acute growth faltering.
3) Since the differences in the prevalence of underweight are often relatively small (e.g. from 23.5% to 21%), SMART surveys need to be implemented to a maximum quality and precision. Always use a small margin of error (2-2.5%). If your team does not have sufficient experience with conducting SMART surveys, contract an in-country or headquarters-based advisor to design methodology, train your team and supervise the survey quality.
