Allocation concealment
Methods described and acceptable (Higgins 2005): centralised (for example, allocation by a central office unaware of participant characteristics) or pharmacy-controlled randomisation; pre-numbered or coded identical containers which are administered serially to participants; on-site computer system combined with allocations kept in a locked unreadable; computer file that can be accessed only after the characteristics of an enrolled participant have been entered; sequentially numbered, sealed, opaque envelopes;
other methods; no description.