{smcl} {* *! version 1.1.0 10aug2011}{...} {cmd:help zscore06} {hline} {title:Title} {phang} {bf:zscore06} {hline 2} Calculate anthropometric z-scores using the 2006 WHO child growth standards {title:Syntax} {p 8 17 2} {cmdab:zscore06} {ifin} [{cmd:,} {it:options}] {synoptset 20 tabbed}{...} {synopthdr} {synoptline} {syntab:Main} {synopt:{opth a(varname)}}child's age {it:varname}{p_end} {synopt:{opth s(varname)}}child's sex {it:varname}{p_end} {synopt:{opth h(varname)}}child's length {it:varname}{p_end} {synopt:{opth w(varname)}}child's weight {it:varname}{p_end} {synopt:{opth w(varname)}}child's weight {it:varname}{p_end} {synopt:{opt female(#)}}value used for girls in sex {it:varname}{p_end} {synopt:{opt male(#)}}value used for boys in sex {it:varname}{p_end} {synopt:{opth measure(varname)}}recumbent length or standing height {it:varname}{p_end} {synopt:{opt recum(#)}}value used for recumbent length in recum {it:varname}{p_end} {synopt:{opt stand(#)}}value used for standing height in recum {it:varname}{p_end} {synopt:{opth o(varname)}}oedema {it:varname}{p_end} {synopt:{opt oyes(#)}}value used for presence of oedema in oedema {it:varname}{p_end} {synopt:{opt ono(#)}}value used for absence of oedema in oedema {it:varname}{p_end} {title:Description} {pstd} {cmd:zscore06} calculates anthropometric z-scores using the 2006 WHO child growth standards. Lenght/heigh-for-age, weight-for-height, BMI-for-age and weight-for-age Z-scores are calculated for children 0 to 5 years of age. {title:Options} {dlgtab:Main} {phang} {opth a(varname)} specifies the child age {it:varname}. Age must be in months. {phang} {opth s(varname)} specifies the child sex {it:varname}. The default is to code boys as 1 and girls as 2. If other values are used, they must be specified in {cmd:male(#)} and {cmd:female(#)}. {phang} {opth h(varname)} specifies the child length/height {it:varname}. Lenght/height must be in cm. Recumbent lenght is assumed for children < 24 months, standing height for children > 24 months. If this is not the case, {cmd:measure({varname})} must be specified. At least one of {cmd:h({varname})} or {cmd:w({varname})} must be specified. {phang} {opth w(varname)} specifies the child weight {it:varname}. Weight must be in kg. At least one of {cmd:h({varname})} or {cmd:w({varname})} must be specified. {phang} {opt female(#)} value used for girls in the child sex {it:varname} specified in {cmd:s({varname})} if different from 2. {phang} {opt male(#)} value used for boys in the the child sex {it:varname} specified in {cmd:s({varname})} if different from 1. {phang} {opth measure(varname)} specifies the {it:varname} indicating whether recumbent length or standing height was measured. If the 24 month cut-off was correctly applied {cmd:measure({varname})} need not be pecified. If the 24 month cut-off was not used correctly {cmd:measure({varname})} needs to be 1 for recumbent length and 2 for standing height. If other values are used, they must be specified in {cmd:recum(#)} and {cmd:stand(#)}. {phang} {opt recum(#)} value used for recumbent length in the measure {it:varname} specified in {cmd:measure({varname})} if different from 1. {phang} {opt stand(#)} value used for standing height in the measure {it:varname} specified in {cmd:measure({varname})} if different from 2. {phang} {opth o(varname)} specifies the {it:varname} indicating whether oedema was observed. {cmd: zscore06} assumes that children had no oedema. If this is the case, there is no need to define {cmd:o({varname})}. If some children had oedema the default is to code children with oedema as 1 and children wihtout oedema as 2. If other values are used, they must be specified in {cmd:oyes(#)} and {cmd:ono(#)}. Weight-for-age, weight-for-height and BMI-for-age are not calculated for children with oedema. {phang} {opt oyes(#)} value used for the presence of oedema in the oedema {it:varname} specified in {cmd:o({varname})} if different from 1. {phang} {opt ono(#)} value used for the absence of oedema in the oedema {it:varname} specified in {cmd:o({varname})} if different from 2. {title:Remarks} {pstd} Even though {cmd: zscore06} uses the same algorithm to calculate anthropometric z-scores as WHO's igrowup macro, there are some differences in the created variables: {phang} . {cmd: zscore06} does not calculate any of the z-scores if child age is missing. Igrowup does calculate the weight-for-height z-score. {phang} . If the age, height or weight values are outside the range of the reference values (e.g. a child older than 5 years of age), the corresponding z-score(s) will be set to 99. Igrowup will assign a missing value to these observations. {phang} . Differences in the precision of the storage types used in zscore06 (all stored as double) and igrowup (some stored as float) can lead to small differences (<=0.01) in the calculated Z-scores. These differences, however, are rare (<1/1000). In the cases we have identified to date, we believe that zscore06 produces the correct result. For example, take the following child: {center:{cmd:variable value}} {center:{hline 30}} {center: sex girl} {center: age (days) 407} {center: length (cm) 70.5} {pmore} The reference values for this child are: {center:{cmd:parameter reference value}} {center:{hline 30}} {center: l 1} {center: m 75.6546} {center: s 0.03503} {pmore} Using the equation from the WHO publication cited below, we find: {pmore2} haz06 = (((70.5/75.6546)^1)-1)/(0.03503*1)} = -1.94499949 ~= -1.94 as calculated by {cmd: zscore06} and not -1.95 as calculated by igrowup {title:Acknowledgements} {pstd} James Beard (University College London) provided very useful comments on the previous version of this command. {title:References} {pstd} Mercedes de Onis et al. 2006. WHO child growth standards : length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age : methods and development. World Health Organization. Geneve. {title:Citation of zscore06} {pstd} {cmd:zscore06} is not an official Stata command. It is a free contribution to the research community. Please cite it as such: {phang}Leroy, Jef L (2011). zscore06: Stata command for the calculation of anthropometric z-scores using the 2006 WHO child growth standards {browse "http://www.ifpri.org/staffprofile/jef-leroy"} {title:Author} {phang}Jef L Leroy, International Food Policy Research Institute, Washington DC, USA (j.leroy@cgiar.org)