The third meeting of our New Phil Stat Forum*:

The Statistics Wars
and Their Casualties

November 19: 15:00 – 16:45  (London time)
10-11:45 am (New York, EST) 

“Randomisation and Control in the Age of Coronavirus

Stephen Senn

ABSTRACT: Many critics of randomisation have assumed that it is supposed to guarantee balance of prognostic factors, proceeded to show that this is impossible and then concluded that the theory is flawed. However, the shocking truth about randomisation is exactly the opposite of what they suppose. If we knew that all prognostic factors in a randomised clinical trial were balanced, the standard analysis of such trials would be wrong. The analysis that Fisher proposed for randomised experiments makes an allowance for factors being unbalanced. I shall show how this fundamental misunderstanding of how the randomisation and analysis combination deals with error is the origin of a serious error in interpreting trials. I shall illustrate the points with a game of chance and an actual trial. I conclude by recommending that would-be commentators should not presume to analyse the logic of trials until they have analysed some results.

Stephen Senn is a consultant statistician in Edinburgh. His expertise is in statistical methods for drug development and statistical inference. He consults extensively for the pharmaceutical industry in the UK, Europe and the USA on: planning of clinical trials and drug development programmes, project evaluation and prioritization, regulatory advice and representation, data safety monitoring board advice, specialist analyses, and statistical training. Stephen Senn has worked as a statistician but also as an academic in various positions in Switzerland, Scotland, England and Luxembourg. From 2011-2018 he was head of the Competence Center for Methodology and Statistics at the Luxembourg Institute of Health in Luxembourg. He was a Professor in Statistics at the University of Glasgow (2003) and University College London (1995-2003). He received the George C Challis Award of the University of Florida for contributions to biostatistics, 2001 and the PSI Award for most interesting speaker in 25 years of PSI in 2002. In 2009, he was awarded the Bradford Hill Medal of the Royal Statistical Society. In 2017 he gave the Fisher Memorial Lecture. He is an honorary life member of PSI and ISCB.

Information about the Phil Stat Wars forum and how to join is here. 


For related posts on randomization by Stephen Senn, see these guest posts from the Error Statistics Philosophy blog:

Slides and Video Links:

Stephen Senn’s slides: Randomisation and Control in the Age of Coronavirus

Stephen Senn’s presentation:

Discussion on Senn’s presentation:


Mayo’s Memos: Any info or events that arise that seem relevant to share with y’all before the meeting.

*Meeting 11 of our the general Phil Stat series which began with the LSE Seminar PH500 on May 21