How to do random allocation (randomization)
Jeehyoung Kim, Wonshik Shin, Jeehyoung Kim, Wonshik Shin
Abstract
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.
Keywords: Block randomization; Random allocation; Simple randomization; Stratified randomization.
Conflict of interest statement
No potential conflict of interest relevant to this article was reported.
Figures
![Fig. 1](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/3942596/bin/cios-6-103-g001.jpg)
Simple randomization sheet.
![Fig. 2](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/3942596/bin/cios-6-103-g002.jpg)
An example of randomization when the block size is four.
![Fig. 3](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/3942596/bin/cios-6-103-g003.jpg)
Block randomization when the block size is two and four. Total eight blocks in the red-dotted line are assigned at random. The left column is for allocation and the right column is for the total sample size.
![Fig. 4](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/3942596/bin/cios-6-103-g004.jpg)
www.randomization.com can do block randomization more easily. In this figure, the block size is 2, 4, and 6 when the total samples are 88.
![Fig. 5](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/3942596/bin/cios-6-103-g005.jpg)
The reality of the randomization procedure.
![Fig. 6](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/3942596/bin/cios-6-103-g006.jpg)
MS word can replace A and B with a specific treatment name easily.
References
- Bhandari M, Richards RR, Sprague S, Schemitsch EH. The quality of reporting of randomized trials in the Journal of Bone and Joint Surgery from 1988 through 2000. J Bone Joint Surg Am. 2002;84(3):388–396.
- Montané E, Vallano A, Vidal X, Aguilera C, Laporte JR. Reporting randomised clinical trials of analgesics after traumatic or orthopaedic surgery is inadequate: a systematic review. BMC Clin Pharmacol. 2010;10:2.
Source: PubMed