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Description
Envelope concealment was used to determine which treatment a patient would receive, in which random groups were placed in sequentially coded, sealed, opaque envelopes that were opened by a physician when a qualified subject agreed to participate in the clinical trial
and multiple levels, and were maintained in the same group housing throughout the study
New England Journal of Medicine, 368: 1575-1584 Zhu W, et al
Jun 2017;174(11):1349-1365
