13. 委员会在估计辐射诱发的癌症风险时，始终在很大程度上依赖于流行病学的调研结果。委员会十分重视界定高质量流行病学研究的标准和委员会改进其估计所必须考虑的此类研究的各种特征。科学委员会 2000 年的报告概述了统计功效的概念——即流行病学的研究将以一定置信度水平发现风险升高到某一程度的概率——以及影响统计功效的各种因素。2006 年报告附件 A“关于辐射和癌症的流行病学研究”对这一问题的进一步详述表明，一项研究的统计功效在很大程度上受到样本规模、受辐射群体所接受的辐射剂量和风险系数大小的影响，因此文献中所报告的大多数低剂量研究都不具备足够的统计功效。此外，对于各种影响可能较小并且没有任何统计功效的低剂量研究来说，据称“具有统计意义”的结果中所发现的相对风险值可能会大大超过“真正的”风险。
13. The Committee has always relied heavily upon results of epidemiological investigations in estimating the risks of radiation-induced cancer. Much attention has been given by the Committee to the criteria that define good-quality epidemiology studies and to the various features of such studies that must be taken into consideration for the Committee to improve its estimates. The concept of statistical power, that is the probability that an epidemiological study will detect a given level of elevated risk with a specific degree of confidence, and various factors that affect it were summarized in the Scientific Committee’s 2000 report. Further elaboration of this issue in annex A of the 2006 report, entitled “Epidemiological studies of radiation and cancer”, shows that the statistical power of a study is greatly affected by the sample size, the dose level(s) of the exposed group and the magnitude of the risk coefficient, such that most low dose studies reported in the literature have inadequate statistical power. Also, for low dose studies with numbers of effects that are expected to be small and which do not have any statistical power, the value of the relative risk found for any supposedly “statistically significant” results is likely to be a substantial overestimate of the “true” risk.