%0 Journal Article
%T Old and new cluster designs in emergency field surveys: in search of a one-fits-all solution
%A Oleg O Bilukha
%J Emerging Themes in Epidemiology
%D 2008
%I BioMed Central
%R 10.1186/1742-7622-5-7
%X The 67 กม 3, 33 กม 6, and 30 กม 7 designs are expected to be more statistically efficient for measuring outcomes having high design effects (e.g., vaccination coverage, vitamin A distribution coverage, or access to safe water sources), and less efficient for measuring outcomes with more within-cluster variability, such as global acute malnutrition or anemia. Because of small sample sizes, these designs may not provide sufficient levels of precision to measure crude mortality rates. Given the small number (3 to 7) of survey subjects per cluster, it may be hard to select representative samples of subjects within clusters.The smaller sample size in these designs will likely result in substantial time savings. The magnitude of the savings will depend on several factors, including the average travel time between clusters. The 67 กม 3 design will provide the least time savings. The 33 กม 6 and 30 กม 7 designs perform similarly to each other, both in terms of statistical efficiency and in terms of time required to complete the survey.Cluster designs discussed in this paper may offer substantial time and cost savings compared to the traditional 30 กม 30 design, and may provide acceptable levels of precision when measuring outcomes that have high intracluster homogeneity. Further investigation is required to determine whether these designs can consistently provide accurate point estimates for key outcomes of interest. Organizations conducting cluster surveys in emergency settings need to build their technical capacity in survey design to be able to calculate context-specific sample sizes individually for each planned survey.Over the past three decades, field surveys using a cluster sample design have become a standard, popular, and widely used method of measuring key nutrition and health indicators in humanitarian emergencies [1-4]. This method was first widely popularized by the Expanded Program on Immunization (EPI) of the World Health Organization, which since 1978 has promoted
%U http://www.ete-online.com/content/5/1/7