利用随机数字编码进行对照的选择在流行病学调查中日见愈加广泛,这往往是由于经济方面的考虑。儿科恶性疾病的流行病学分析性调查,往往由于没有足够数量的同一时点上特定组织学类型的病例可资利用而发生障碍,因而需要利用在颇长期间内诊断的一系列病例。为克服这个困难,调查者们正在转向一些临床的合作组作为病例探查的 The selection of controls using random number coding has become increasingly widespread in epidemiological surveys, which is often due to economic considerations. Epidemiological analysis of pediatric malignancies often results from the failure to use a sufficient number of cases of a specific histological type at the same time, and thus requires the use of a series of cases diagnosed over a long period of time. In order to overcome this difficulty, the investigators are turning to a number of clinical cooperation groups for case detection.