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Using messaging-through-a-network to influence volunteering in the UK
Last registered on July 02, 2014


Trial Information
General Information
Using messaging-through-a-network to influence volunteering in the UK
Initial registration date
Not yet registered
Last updated
July 02, 2014 12:01 PM EDT
Primary Investigator
Behavioural Insights Team
Other Primary Investigator(s)
Additional Trial Information
On going
Start date
End date
Secondary IDs
People’s decisions to make donations – be they of money of time – have been shown by previous research to be heavily influenced by the behaviour of others, particularly their friends and family. Such research is typically limited to the quasi-experimental realm, as the number of ‘voices’ with which charities and experimenters can speak is typically limited. In this paper, we investigate the impact of a ‘network nudge’ on tendency to donate time, as part of one of the British government’s largest volunteering campaigns.
External Link(s)
Registration Citation
Sanders, Michael . 2014. "Using messaging-through-a-network to influence volunteering in the UK." AEA RCT Registry. July 02. https://doi.org/10.1257/rct.426-1.0.
Experimental Details
Testimonial Treatments:
There are two testimonial treatments – one in which participants were primed to feel emotionally positive about running dementia friends sessions, and one which provided practical advice on how they can be run. The additional text of these emails can be seen below.
Emotional Prime
"I really enjoyed running my session. It felt great to contribute to a cause I'm passionate about."
Practical Prime
"My session went really well. Social media sites were useful for spreading the word."
Network Nudge Treatments:
In addition to our testimonials there are two ‘network nudge’ treatments. Network nudge interventions are directed at one group – in this case Dementia Champions – and aim to get them to influence the behaviour of a second group to whom they are connected – Dementia Friends – by priming them to activate their social network.
In this experiment our two network nudge treatments vary by number of degrees of separation the network nudge aims to work across. In our “first dimension” treatment, Champions are encouraged to reach out to their friends and family to become dementia friends (text below). In the “second dimension” treatment, Champions are encouraged to invite their friends, and to suggest that they in turn invite their friends – aiming to activate a further extension to the network.
Depending on the levels of overlap in champions and friends’ social networks, the second dimension treatment could give access to a much larger number of potential individuals. However, the second dimension of ask may be less powerful than the first, and could discourage some potential friends from attending by themselves if they believe they are expected to bring a friend.
Intervention Start Date
Intervention End Date
Primary Outcomes
Primary Outcomes (end points)
Number of Dementia friends recruited
Number of sessions conducted
Primary Outcomes (explanation)
Secondary Outcomes
Secondary Outcomes (end points)
Secondary Outcomes (explanation)
Experimental Design
Experimental Design
Participants (Dementia Champions) are randomly assigned to conditions, and sent their treatments in emails as part of their normal recruitment process. Participants are sent the email across several days as they become Dementia Champions. Over the subsequent six months, we monitor the number of sessions they organise and record on the Dementia Friends online portal.
Experimental Design Details
Randomization Method
Randomised by a javascript randomiser during email generation.
Randomization Unit
Individual (dementia champion)
Was the treatment clustered?
Experiment Characteristics
Sample size: planned number of clusters
821 individuals, N sessions where N is the number of sessions organised by these champions.
Sample size: planned number of observations
821 Dementia Champions
Sample size (or number of clusters) by treatment arms
Network Nudge 1: 280
Network Nudge 2: 185
Testimonial 1: 371
Testimonial 2: 202
(Cause of imbalance small cell by cell N's/staggered randomisation by dates).
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
No baseline data is available for this trial, and Ns were not available prior to launch, making power calculations impractical.
Supporting Documents and Materials

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Request Information
IRB Name
Behavioural Insights Team Internal Review
IRB Approval Date
IRB Approval Number
None provided (pre-formal setup)
Post Trial Information
Study Withdrawal
Is the intervention completed?
Is data collection complete?
Data Publication
Data Publication
Is public data available?
Program Files
Program Files
Reports, Papers & Other Materials
Relevant Paper(s)