ABSTRACT
Having time to focus on a single decision in isolation from all other pressing problems is a luxury afforded mostly by armchair advisors, theoreticians and those who face a single momentous problem that dwarfs all others in its opportunity to gain or its threat to lose. This chapter addresses the simplest of some settings in which no decision affects the losses, or loss functions, of any others and the decisions have to be made at the same time but in no particular order. A key step in the recruitment of a patient, is informed consent, a conscious decision to enrol in the trial, arrived at without any coercion or threat of a sanction, after being informed of the two (or several) alternative treatments and made aware of the procedure of randomisation and other design features of the trial. The fundamental difference between clinical trials and observational studies is in their design; former control treatment assignment, and the latter do not.
