Karon J M, Kupper L L
Am J Epidemiol. 1982 Nov;116(5):852-66. doi: 10.1093/oxfordjournals.aje.a113476.
This paper discusses the simplified situation of an epidemiologic study involving disease, exposure, and a single (possibly confounding) extraneous factor, all of which are dichotomous. The question is: In studying the association between disease and exposure, should the comparison group be selected by random sampling or by matching on the extraneous factor? An example is used to demonstrate the general principle that matching controls confounding in estimating the risk ratio in a follow-up study, but not in estimating the exposure odds ratio in a case-control study. Calculations based on a probability model show that, despite the possible reduction in sample size which may be associated with matching, matching will often lead to a more precise estimate of the effect measure than random sampling and is not likely to result in a significant loss in precision in situations of practical importance. Therefore, selection of the referent group by matching should be given serious consideration for both follow-up and case-control studies.
本文讨论了一项流行病学研究的简化情形，该研究涉及疾病、暴露因素以及单一（可能为混杂）外部因素，所有这些均为二分变量。问题在于：在研究疾病与暴露之间的关联时，对照组应通过随机抽样选取还是根据外部因素进行匹配选取？通过一个例子来说明一般原则，即在随访研究中匹配可控制混杂因素对风险比的估计，但在病例对照研究中对暴露比值比的估计则不然。基于概率模型的计算表明，尽管匹配可能会减少样本量，但与随机抽样相比，匹配通常会使效应量的估计更为精确，并且在实际重要的情形下不太可能导致精度显著损失。因此，对于随访研究和病例对照研究，都应认真考虑通过匹配来选择参照组。
