van Houwelingen J C
Rijksuniversiteit, faculteit der Geneeskunde, sectie Medische Statistiek, Leiden.
Ned Tijdschr Geneeskd. 1998 Jul 18;142(29):1662-5.
In some studies randomization at the patient level is not possible; randomization at the doctor's level can then be applied. However, statistical analysis at the level of the individual patient data can lead to wrong conclusions in such a study design. By basing the analysis on the averages per doctor a statistical test can be performed which guarantees the correct significance level. The correct sample size can be found by means of a correction factor that depends on the variation between the doctors. The data of a study with randomization at the doctor's level can be analysed in a more sophisticated way by means of so-called 'mixed models' that take account of possible variation between doctors.
在一些研究中，患者层面的随机分组是不可能实现的；此时可以采用医生层面的随机分组。然而，在这样的研究设计中，对个体患者数据进行统计分析可能会得出错误结论。通过基于每位医生的平均值进行分析，可以进行统计检验，从而保证正确的显著性水平。可以借助一个取决于医生之间差异的校正因子来确定正确的样本量。对于医生层面随机分组的研究数据，可以通过考虑医生之间可能存在的差异的所谓“混合模型”以更复杂的方式进行分析。
