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 provide validated and easy to use online/IVR (telephone) software for randomising patients into clinical trials.

Reasons to choose HSRU for your service:

  • Highly experienced staff and reliable online/telephone service.
  • Can integrate and export data dynamically to other 3rd party systems.
  • Suitable for a wide variety of trial types, customised to your trial.
  • Advice on system design and implementations.
  • Ongoing export support via online support tool.

Simple randomisation, block randomisation, stratified block randomisation and minimisation are offered as standard.  Novel randomisation can be implemented on request. 

Telephone randomisation service

HSRU offer a 24-hour, seven-day automated telephone randomisation service, telephone calls are made to the service using a Freephone number, which is connected to 16 telephone lines. For international calls, there is a standard UK telephone number.

Web-based randomisation service

HSRU offer a secure and robust web-based randomisation system. It is accessible anytime, anywhere and via any device that has a modern web browser and is connected to the Internet. 

Standard features

A customisable role-based user access control system, email notifications are built in. The randomisation system generates confirmation emails that can be blinded or unblinded to treatment allocation.

Standard reports summarising randomisation and all data-entry activity, custom reports implemented on request.

All transactions are logged, the trial's audit trail and the list of randomisations can be downloaded and analysed at any time by authorised users

Randomisation simulation data is generated before the study begins, to check balance across stratification factors. The system can be programmed to perform validation checks, such as checking for duplicate Participant Identification Numbers and preventing randomisation from proceeding in such cases.

Drug supply chain management

The randomisation service can also handle drug supply chain.  Active and placebo unique treatment pack numbers, batch numbers and expiry dates can be programmed into the system, with the system recording packs delivered to specific site/pharmacies and only allocating medication packs that are available at that site.  Notifications can be set up to alert site/pharmacies of low drug supply, and this functionality is configurable as required. For example, notify site/pharmacy when the stock level reaches x amount of packs.


We can offer you an emergency online/telephone code break (unblinding) service which is also available 24 hours a day.  Investigators break the blind by simply providing the unique randomisation number, or other identifier used for your trial medication or intervention. Investigators are immediately notified of the unblinded treatment allocation. Trial teams can choose to be notified by email of every new code break.


Invitations are sent by email, links to complete the forms online are included in the emails.  Invites and reminders can be sent automatically via our built-in configurable communication manager.

Implementation and cost

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 or If you would like a demonstration on either the telephone or web-based randomisation service, please contact the Senior IT Development Manager: Mark Forrest

Review and Dissemination

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