Abstract

Randomization is a key feature of randomized clinical trials aiming to protect against various types of bias. Different randomization procedures were introduced in the past decades and their analytical properties have been studied by various authors. Among others, balancing behaviour, protection against selection and chronological bias etc have been investigated. However, in summary no procedure performs best on all criteria. On the other hand, in the design phase of a clinical trial the scientist has to select a particular randomization procedure to be used in the allocation process which takes into account the research conditions of the trial. Up to now, less support is available to guide the scientist hereby, e.g. to weigh up the properties with respect to practical needs of the research question to be answered by the clinical trial. We propose a method to assess the impact of chronological and selection bias in a parallel group randomized clinical trial with continuous normal outcome on the probability of type one error to derive scientific arguments for selection of an appropriate randomization procedure.

This is joint work with Simon Langer.