Cheif Investigator

Dr Christopher Partlett

Assistant Professor of Medical Statistics and Clinical Trials

University of Nottingham


National Institute for Health and Care Research (NIHR) - Clinical Trials Unit Support Funding Opportunity 

Supporting efficient / innovative delivery of NIHR research (June 2020).




There is good empirical evidence of the benefit of blinding participants, clinicians, and outcome assessors in clinical trials to reduce the risk of bias and to improve the trust and credibility of the results. However, it is not clear if blinding of other members of the trial team, such as statisticians, also reduces the risk of bias.

Existing guidelines recommend blinding the trial statisticians before the end of the trial, but do not consider the trial-specific risk of blinding or not blinding the statistician. The goal of this study was to identify and provide evidence for a risk-proportionate strategy for blinding statisticians in clinical trials.

The study was comprised of three main parts:

  • A qualitative study to determine the views and opinions of key stakeholders 
  • A quantitative study to assess the impact of blinding on trial outcomes/results
  • Combining the results of qualitative and quantitative study along with a stakeholder meeting to produce guidance for clinical trials units

Posters and presentations

Posters presented at ICTMC 2022:

A webinar delivered as part of the Health Research Board – Trial Methodology Research Network seminar series on the methodology and findings of the BOTS project is available here.


Iflaifel, M., Partlett, C., Bell, J. et al. Blinding of study statisticians in clinical trials: a qualitative study in UK clinical trials units. Trials 23, 535 (2022).

Iflaifel, M., Sprange, K., Bell, J. et al. Developing guidance for a risk-proportionate approach to blinding statisticians within clinical trials: a mixed methods study. Trials 24, 71 (2023).

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