Armstrong B G
Department of Occupational Health, McGill University, Montreal, Quebec, Canada.
Am J Epidemiol. 1996 Jul 15;144(2):192-7. doi: 10.1093/oxfordjournals.aje.a008908.
We consider an epidemiologic study with a fixed budget, in which resources may be put into increasing sample size or into improving accuracy of exposure assessments. To maximize study power (efficiency), improving accuracy is preferable if and only if the proportional increase in the square of the validity coefficient is more than the proportional increase in total study costs per subject that is required to achieve it. (The validity coefficient is the correlation between the true exposure and the approximate assessment in the study base.) This is most likely to be so if the cost of exposure measurement remains a small proportion of the overall costs per subject. The design with maximum power will not generally have minimum bias in measure of effect, so that alternative optimality criteria are required if this bias is important.
我们考虑一项预算固定的流行病学研究，在该研究中，资源可用于增加样本量或提高暴露评估的准确性。为了使研究效能（效率）最大化，当且仅当效度系数平方的成比例增加超过实现该增加所需的每个研究对象总研究成本的成比例增加时，提高准确性才是更可取的。（效度系数是研究基础中真实暴露与近似评估之间的相关性。）如果暴露测量成本在每个研究对象的总成本中所占比例仍然较小，那么情况很可能如此。具有最大效能的设计通常在效应测量中不会具有最小偏差，因此，如果这种偏差很重要，则需要其他最优性标准。
