data_anthro_for deposit.pdf

The WHO standards are available on the website of WHO (http://www.who.int/childgrowth/en/). You find there the software Anthro2005 for calculation of individual data (Anthro2005). For calculating the z-scores of the new standards the LMS procedure is used. The principle is to get from a table for a certain age and sex 3 values (LMS) which are put into a formula For example WAZ = ((weight/M)^L-1)/(L*S)) e.g.: Female, 9kg, 365 days => L = -0.2022, M = 8.9462, S = 0.12267 WAZ = ((9/M)^L-1)/(L*S) = ((9/8.9462)^-0.2022-1)/(-0.2022*0.12267) = 0.04885 Z-scores On the WHO website you find only the LMS values for each month. Wt L M S 9 -0.2022 8.9462 0.12267 0.048847178 To calculate the actual weight from the LSM statistics at any cut off point use the following formula: wt = M * ((Z * S * L) +1)^(1/L) Where Z = Zscore you are trying to obtain This is the reverse of the formula to calculate WAZ etc. And will give the standard to more decimal places for interpolation [purposes I have taken 10 boys and 10 girls at 0.5 cm intervals from 60 to 110cm in height with weight for height mean at -1Z with SD or 1.0. These are in the sheet WFH_Population. For the simulation I have now added a random variable to the weight or the height in the POP_weight and the POP_height sheets.世界卫生组织（WHO）的生长标准可在其官方网站（http://www.who.int/childgrowth/en/）获取，该网站还提供用于个体数据计算的Anthro2005软件（Anthro2005）。 新版生长标准的Z分数（Z-scores）计算采用LMS方法（LMS procedure），其核心原理为：从对应年龄与性别的参数表中提取L、M、S三个参数，代入预设公式完成计算。以体重年龄别Z分数（WAZ）为例，计算公式为：WAZ = ((weight/M)^L - 1)/(L*S)。示例如下： 若受试者为女性，体重9kg，年龄365天，对应参数为L=-0.2022、M=8.9462、S=0.12267，则： WAZ = ((9/8.9462)^-0.2022 - 1)/(-0.2022*0.12267) ≈ 0.04885（Z分数）。 世界卫生组织官网仅提供按月度划分的LMS参数值，示例参数表如下： Wt L M S 计算所得Z分数 9 -0.2022 8.9462 0.12267 0.048847178 若需基于LMS统计量在任意截断点反推实际体重，可使用以下逆运算公式：wt = M * ((Z * S * L) + 1)^(1/L)，其中Z为目标Z分数。该公式为前述WAZ计算公式的逆形式，可得到保留更多小数位的标准值以用于插值计算。 为完成插值相关工作，笔者选取了身高区间60cm至110cm、以0.5cm为间隔的10名男童与10名女童，其身高别体重均值为-1Z，标准差为1.0。相关数据收录于WFH_Population工作表中。 本次模拟实验中，笔者已在POP_weight与POP_height工作表中为体重与身高字段添加了随机变量。