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Randomization and allocation concealment: a practical guide for researchers
Affiliation.
- 1 Northern Clinical School, Royal North Shore Hospital-ICU, University of Sydney, St Leonards, NSW, Australia. [email protected]
- PMID: 16139163
- DOI: 10.1016/j.jcrc.2005.04.005
Although the randomized controlled trial is the most important tool currently available to objectively assess the impact of new treatments, the act of randomization itself is often poorly conducted and incompletely reported. The primary purpose of randomizing patients into treatment arms is to prevent researchers, clinicians, and patients from predicting, and thus influencing, which patients will receive which treatments. This important source of bias can be eliminated by concealing the upcoming allocation sequence from researchers and participants. Although there are many approaches to randomization that are known to effectively conceal the randomization sequence, the use of sequentially numbered, opaque sealed envelopes (SNOSE) is both cheap and effective. The purpose of this tutorial is to describe a step-by-step process for the preparation of SNOSE. We will outline how to prepare SNOSE to preserve allocation concealment in a trial that (a) uses unrestricted (simple) randomization, (b) stratifies randomization on one factor, (c) uses permuted blocks and, and (d) is conducted at more than 1 study site.
- Varying the block size does not conceal the allocation. Berger VW. Berger VW. J Crit Care. 2006 Jun;21(2):229; author reply 229-30. doi: 10.1016/j.jcrc.2006.01.002. J Crit Care. 2006. PMID: 16769475 No abstract available.
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Methods: We explain the general concept of random allocation and demonstrate how to perform the procedure easily and how to report it in a paper. Keywords: Block randomization; Random allocation; Simple randomization; Stratified randomization. MeSH terms Humans Random Allocation
This important source of bias can be eliminated by concealing the upcoming allocation sequence from researchers and participants. Although there are many approaches to randomization that are known to effectively conceal the randomization sequence, the use of sequentially numbered, opaque sealed envelopes (SNOSE) is both cheap and effective.
Purpose To explain the concept and procedure of random allocation as used in a randomized controlled study. Methods We explain the general concept of random allocation and demonstrate how to perform the procedure easily and how to report it in a paper. View PDF Save to Library Create Alert Cite Figures and Tables from this paper figure 1 table 1
Randomization, allocation concealment and blind-ing should be well implemented and should be described in the paper. Purpose: To explain the concept and procedure of random allocation as used in a randomized controlled study. Methods: We explain the general concept of random allocation and demonstrate how to perform the procedure easily and how to