Sir:
I read the article by Dr Johanna van Rhijn and colleagues [1] with interest, especially because the methods section in the abstract stated “Twenty-one patients were randomized to … ” [my italics]. I am interested in all randomized studies. However, on continuing the sentence I read, “ … to three groups according to impairment severity … ”, which greatly concerned me. The detailed description in the paper confirmed my concerns—this was not a study using randomization. The abstract is in error.
As a reader of many research articles, a reviewer of many articles and grant applications, and as the editor of a journal, I am repeatedly struck by how unaware many people are both of the meaning of the word random, and of the reason for using randomization.
Random means “by chance”. It implies unpredictability. Randomization in the context of scientific research means that chance (in the true sense of the word) determines the outcome of a decision. It means that a stochastic process must be involved.
Random does not equate to:
arbitrary (i.e. not due to any obvious system);
alternate, or based on order of recruitment in some way;
being based on some variable or fact thought to be un-associated with outcome, such as time of day, birth date, availability of a bed, etc.;
being based on some patient variable (such as in this study Citation[1]).
different treatments/interventions;
timing of starting a treatment (in a single case-study);
order of treatments/interventions/observations/tests;
the observer making observations.
I hope that researchers and authors will restrict their use of the words random and randomization to decisions that are indeed unpredictable and governed entirely by a stochastic process.
Derick T Wade
Consultant and Professor in Neurological Rehabilitation Neurological Rehabilitation Service, Oxford Centre for Enablement
Windmill Road, Oxford OX3 7LD, UK
Reference
- Van Rhijn J, Molenaers G, Ceulemans B. Botulinum toxin type A in the treatment of children and adults with an acquired brain injury. Brain Injury 2005; 19: 331–335