Projects undertaken by the Unit have contributed to the development of many different research tools for both researchers and users of research. In collaboration with colleagues at other Universities we have developed tools to help trialists match their trial design decisions to the needs of the intended users of the trial results.

Study Design and Sample Size Calculator

Sample Size calculator for cluster randomised trials

Version 2 of the sample size calculator is in development.  
Please click here for a beta version.  See also this document.

The instruction manual for this program can be downloaded as a pdf file at the link below.  

A further description of the calculator can be found in Campbell MK, Thomson S, Ramsay CR, MacLennan GS, Grimshaw JM. Sample size calculator for cluster randomised trials. Comput Biol Med 2004;34:113-125.

If you have any queries about the calculator, please contact Jemma Hudson (


In collaboration with colleagues at other Universities we have developed PRECIS-2, which is a tool to help trialists match their trial design decisions to the needs of the intended users of the trial results. PRECIS-2 has nine domains—eligibility criteria, recruitment, setting, organisation, flexibility (delivery), flexibility (adherence), follow-up, primary outcome, and primary analysis—scored from 1 (very explanatory design approach) to 5 (very pragmatic design approach) to facilitate domain discussion and consensus.

A website to support the use of the tool is available at

A description of PRECIS-2 can be found in Loudon K, Treweek S, Sullivan F, Donnan P, Thorpe KE, Zwarenstein M. The PRECIS-2 tool: designing trials that are fit for purpose. BMJ 2015;350:h2147 (

If you have any queries about the calculator, please contact Shaun Treweek (

Database of intra-correlation coefficients (ICCs)

A downloadable excel spreadsheet contains a list of intra-correlation coefficient calculated from a number of different interventions and settings. Also downloadable, is a list of references for the data contained in the spreadsheet.

Contamination in randomised trials

A flowchart was developed by the HTA Contamination in trials project to aid the decision on when a cluster randomised controlled trial might be preferred to a patient randomised controlled trial when contamination of controls are suspected.

Multilevel factorial cluster randomised controlled trials

Complex randomised controlled trials are required to evaluate complex interventions.

Multilevel factorial cluster randomised controlled trials (C-RCT), also known as split-plot designs, address research questions that are multilevel (interventions aimed at different levels in a structure such as doctors and patients) and have the potential to explore interactions between interventions (whether or not giving two interventions together works any better than giving them separately.

To learn more about this type of design and its statistical implications, please consult Beatriz Goulao’s presentation here.

We have published a set of guidelines to improve the reporting of multilevel factorial cluster randomised controlled trials, which you can see here.

A statistical simulation tutorial to aid the sample size calculation for multilevel factorial cluster randomised controlled trials will be available soon.

Find out about Beatriz’s Goulao's PhD project here.

Study Conduct

Trial Protocol Tool

The Practihc collaboration developed a Trial Protocol Tool that supports the production of a high quality research protocol.  It provides a checklist of issues that should be considered when writing a protocol.  A paper describing the tool is available here.

Tool for conducting and managing RCTs

The SUPPORT project developed a Trial Management Tool to help trialists conduct and manage pragmatic randomised controlled trials (RCT).


The DAMOCLES study formulated a list of considerations that would be valuable for a Data Monitoring Committee (DMC) to address at the start of a trial which were developed into a charter.


Outcome Measures

Beliefs about surgery questionnaire

The REFLUX Study developed and validated a questionnaire for measuring patients Beliefs about surgery.


Randomisation Service

HSRU offer a 24-hour, seven day telephone randomisation service and/or randomisation over the Web. Multiple randomisation algorithms are supported including minimisation and random permuted blocks. The service can also handle drug supply chain and unblinding.

Randomisation reports can be sent automatically by email or ftp and can be provided either at each randomisation, daily, weekly or monthly to specified study personnel.

Telephone calls are made to the service using a freephone number which is connected to 8 telephone lines. For international calls there is a standard UK telephone number.

The cost of the service depends on how long the service is required and the sample size.  The randomisation request form can be found here.

If you require further information relating to planning a new randomisation service, please contact the Senior IT Manager: Mark Forrest


Review and Dissemination

Projects have contributed to guidance documents for reviewing and disseminating results of research.