In a randomized experiment,<unk>  hides the sorting of trial participants into treatment groups so that this knowledge cannot be exploited. Adequate<unk>  serves to prevent study participants from influencing treatment<unk> s for subjects. Studies with poor<unk>  (or none at all) are prone to selection bias. Some standard methods of ensuring<unk>  include sequentially numbered, opaque, sealed envelopes (SNOSE); sequentially numbered containers; pharmacy controlled randomization; and central randomization. CONSORT guidelines recommend that<unk>  methods be included in a study's protocol, and that the<unk>  methods be reported in detail in their publication; however, a 2005 study determined that most clinical trials have unclear<unk>  in their protocols, in their publications, or both. A 2008 study of 146 meta-analyses concluded that the results of randomized controlled trials with inadequate or unclear<unk>  tended to be biased toward beneficial effects only if the trials' outcomes were subjective as opposed to objective.<unk>  is different from blinding. An<unk>  method prevents influence on the randomization process, while blinding conceals the outcome of the randomization. However,<unk>  may also be called "randomization blinding".
Allocation concealment
Blinded experiment
Appropriate use criteria
Adaptive design 
Data validation
External quality assessment
Mutual standardisation
Emerging Themes in Epidemiology