Division of Nutrition, Centers for Disease Control, 1600 Clifton Road, Atlanta, GA 30333, USA.
Disasters. 1992 Jun;16(2):97-103. doi: 10.1111/j.1467-7717.1992.tb00383.x.
On the basis of theoretical considerations, population-based nutrition surveys of 30 clusters of 30 children should provide reasonably valid estimates of the prevalence of malnutrition with at least 95 per cent confidence that the estimated prevalence differs from the true value by no more than 5 per cent. In areas of famine in Africa, where an urgent need often exists for rapid nutritional assessment to determine the extent and severity of the problem, visiting 30 sites is often logistically difficult. To determine the effects of using fewer than 30 clusters on the validity and precision of the estimated level of undernutrition, we used data from the 1983 Swaziland National Nutrition Survey and from rapid nutrition surveys performed in 1984 and 1985 in Burkina Faso, Guinea, and Niger. Fewer than 30 clusters may result in point prevalence estimates that differ dramatically from the true prevalence and, in most instances, are less precise. In contrast, little is gained by collecting more than 30 clusters. In summary, around 30 clusters provides relatively valid and precise estimates of the prevalence of undernutrition, and every effort should be made to obtain the logistic support required to study this number of clusters.
基于理论考虑，对 30 个 30 名儿童群组的基于人群的营养调查应能合理有效地估计营养不良的流行率，置信度至少为 95%，即估计的流行率与真实值相差不超过 5%。在非洲饥荒地区，通常迫切需要快速进行营养评估，以确定问题的程度和严重程度，而访问 30 个地点在后勤上往往很困难。为了确定使用少于 30 个群组对估计营养不良程度的有效性和精确性的影响，我们使用了 1983 年斯威士兰国家营养调查的数据，以及 1984 年和 1985 年在布基纳法索、几内亚和尼日尔进行的快速营养调查的数据。少于 30 个群组可能导致点流行率估计值与真实流行率有很大差异，而且在大多数情况下，精确性较差。相比之下，收集超过 30 个群组并没有太多好处。总之，大约 30 个群组可以提供相对有效和精确的营养不良流行率估计值，应尽一切努力获得研究这些群组所需的后勤支持。
