DEFINITION:<br/>An administrative activity defined at a global library level that is the assignment of an experimental unit to a portion of the study, such as an arm or a portion of an arm (when secondary allocations may occur).<br/><br/>EXAMPLE(S):<br/>randomization, direct assignment based on eligibility criteria, etc.<br/><br/>"Escalating dose cohort studies" enroll subjects in successive arms, i.e., one arm is completely filled before any subjects are enrolled in the next arm.  In such a study, allocation depends on which arms have been fully enrolled and which are currently open for enrollment.  Note that this example assumes that the experimental unit is the subject (rather than a part of a subject or a group of subjects).<br/><br/>OTHER NAME(S):<br/><br/>NOTE(S):<br/>