Estimation of Population Exposure in Ecological Studies
讨论了生态学研究中群体暴露估计的设计问题，指出研究人群数量超过一定点后意义不大，精度受限于疾病事件总数和样本调查规模，最优设计需按年龄/性别分层抽样。
SUMMARY This paper discusses design issues in 'ecological studies' —epidemiological studies in which the relationship between disease and behavioural and environmental determinants is studied at the population rather than the individual level. The number of study populations has little relevance beyond a certain point, the power and precision being limited by the total number of disease events and by the size of the sample surveys used to estimate the distributions of determinants within populations. In most circumstances, optimal design requires the size of the sample surveys in each population to be related to the number of disease events which will occur in it, and for sampling to be stratified by age and/or sex.