[Roaming through methodology. III. Randomization at the level of the physicians].
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.
Rijksuniversiteit, faculteit der Geneeskunde, sectie Medische Statistiek, Leiden.
J C
JC
van Houwelingen
D015982:Bias; D002986:Clinical Trials as Topic / Q000379:methods*; D004812:Epidemiologic Methods; D006801:Humans; D015233:Models, Statistical; D018579:Patient Selection; D011897:Random Allocation; D012107:Research Design; D018401:Sample Size
Dwalingen in de methodologie. III. Randomisatie op het niveau van behandelaars.