ABSTRACT
Real life experiments, and in particular clinical trials, usually involve additional in-
formation on the experimental units, in the form of a set of covariates, e.g., important
prognostic factors for patients. Taking these covariates into account is of primary im-
portance for a correct inference, and it must be a fundamental concern from a design
perspective in sequential experiments as well. The literature on adaptive randomiza-
tion has been focusing the attention on this issue; see for instance Rosenberger and
Lachin (2002), Hu and Rosenberger (2006), Rosenberger and Sverdlov (2008) and
Shao et al. (2010).
