Nottingham Clinical Trials Unit
The University of Nottingham
University of Nottingham

RAFT: Reporting Factorial Trials

Factorial trials, in which two or more interventions are simultaneously evaluated, have specific design and analysis considerations not covered by standard SPIRIT and CONSORT statements. Reviews show that the reporting quality of factorial trials is often poor. 

The RAFT (Reporting Factorial Trials) study will develop SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) and CONSORT (Consolidated Standards of Reporting Trials) extensions for the reporting of factorial trials. 

All rounds of the survey are now complete. We would like to thank everyone for their support. 

Logo (RAFT)


Factorial trials

 Factorial trials guidance

Factorial trials, in their simplest form (2x2), are when two interventions (A and B) are tested. For example, participants are randomised to receive: no intervention, A alone, B alone or both A and B. 

Factorial trials offer an efficient method to evaluate multiple interventions without increasing the sample size, provided the treatments work independently. The focus of the RAFT study is on factorial designs which aim to efficiently assess multiple interventions in a single trial. 


Some keyword definitions that are frequently used in factorial trials can be found here. 

Funding and key individuals 

The study received funding from the Medical Research Council (MRC) and is a collaboration of different universities across the world. The Principal Investigator is Prof Alan Montgomery. The study co-investigators include Dr Brennan Kahan, Ms Elaine Beller, Prof Diana Elbourne, Prof Ed Juszczak, Prof Paul Little and Dr An-Wen Chan. The lead researcher on the study is Dr Sophie Hall and the research co-ordinator is Ms Megan Birchenall.

Components of the RAFT study 

                           Study information/

 We are currently at the final stage 'knowledge translation', of this piece of research. 

If you have any enquires, please get in touch with us via email:

Study documents

Study updates

  • All 3 rounds of the survey are now complete
  • The RAFT consensus workshop took place in Nottingham on the 6th and 7th September

Check back for study updates!


Nottingham Clinical Trials Unit

General enquiries
Telephone: +44 (0)115 8231600