Definition
For surviving children born in the three to five years before the survey, HWWHZNCHS (HW11) reports the difference between the child's weight and the median weight of a reference population of the same height and sex, expressed in units equal to one standard deviation of the reference population's distribution. An anthropometry measure expressed in reference standard deviation units is also known as a Z-score. HWWHZNCHS values are provided in units equal to 100 times the Z-score, to preserve two decimal places without requiring the use of a decimal point. Dividing HWWHZNCHS by 100 will yield a child's weight-for-height Z-score (WHZ) value.
Low child weight-for-height, or "wasting," is an indicator of acute malnutrition. The WHO Global Database on Child Growth and Malnutrition [URL omitted from DDI.] considers a weight-for-height Z-score (WHZ) between -2 and -3 to represent moderate acute malnutrition, and WHZ below -3 to represent severe acute malnutrition.
Reference populations used to generate HWWHZNCHS draw from 1978 U.S. CDC National Center for Health Statistics (NCHS) international growth reference [URL omitted from DDI.] data. This reference was considered standard by WHO until the 2006 release of the WHO Multicenter Growth Reference Study (MGRS), which generated new standard anthropometry curves using a globally diverse reference population intended to reflect healthy growth conditions. DHS has continued to release child anthropometric variables using NCHS/CDC 1978 reference populations, to preserve comparability with samples preceding the 2006 WHO MGRS release.
DHS has also created anthropometric Z-score variables using WHO MGRS 2006 reference populations. The variable HWWHZWHO (HW72) uses WHO MGRS 2006 reference populations to generate weight-for-height Z-scores. This variable was generated for all DHS samples including the necessary anthropometric measurements, including those preceding 2006.
HWWEIGHT (HW2) reports the child's weight as measured by DHS personnel, and HWHEIGHT (HW3) reports the child's length or height as measured by DHS personnel. See HWHEIGHT (HW3) and HWHTHOWMEAS (HW15) for specifics on child length/height measurement.
The complementary DHS variable HWWTHTPCT (HW10) reports the child's weight-for-height percentile within the same reference population used in HWWHZNCHS. The complementary DHS variable HWWTHTPCTRM (HW12) reports the child's weight-for-height as a percentage of the median of the same reference population. Unlike z-scores, percentiles do not allow comparison across age and sex and cannot assess longitudinal change in growth status; users are advised to consult anthropometry literature [URL omitted from DDI.] for further discussion.
