Allocation concealment

refers to the process of ensuring that the persons assessing patients for potential entry into a trial, as well as the patients themselves, do not know whether any particular patient will be allocated to an intervention group or control group. This diminishes selection bias by preventing the persons who are managing patient allocation, or the patients, from influencing (intentionally or not) patient assignment to one group or another. Centralized randomization (i.e., managed at one site rather than at each enrollment site) using certain techniques is a preferred method ensuring allocation concealment. (This is distinct from blinding of patients, providers, and others.)

Reference see also: concelament of allocation

Goodman CS. HTA 101: Introduction to Health Technology Assessment. Bethesda,MD: National Library of Medicine (US); 2014.