concealment of allocation

concealment of allocation

The process used to prevent foreknowledge of group assignment in a randomised clinical trial, which differs from blinding. Allocation should be administered by someone who is not responsible for recruiting participants—e.g., the hospital, pharmacy or a central office. Methods of assignment such as date of birth and case record numbers (see quasi-random allocation) are open to manipulation.

Examples, allocation concealment
Centralised randomisation schemes; randomisation schemes controlled by a pharmacy; numbered or coded containers in which capsules from identical-looking, numbered bottles are administered sequentially; on-site computer systems, where allocations are in a locked unreadable file; sequentially-numbered, opaque sealed envelopes.