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Text messaging #2: sending participant quotes (ID REC7)

Evidence Summary

What is it?

Giving quotes from existing trial participants in text messages.

Does it work?

Giving quotes from existing participants in text messages probably increases recruitment slightly.

How big is the effect?

An increase of 4% (95% confidence interval = 2% to 6%).

How certain are we?

GRADE Moderate certainty.


We suggest that trialists consider using text messaging #2: quotes from participants, ideally as part of a SWAT evaluation.

How can I use this straight away?

See Resource bundle below for details of how to use text messaging #2: quotes from participants or build a SWAT evaluation of them into your trial.

Practical Impact

Imagine a trial that needs to recruit 30 participants and initial recruitment is 30% of those approached. This means you’d need to approach 100 people to recruit 30 of them (see chart).

Now imagine sending participant quotes as text messages. The chart below shows the impact of an absolute increase of 4% (95% CI = 2% to 6%). Recruitment is now 34%, which means our best estimate is that 88 people would now need to be approached to recruit 30 of them.

Cumulative Meta-Analysis*

*Random effects model done using Comprehensive Meta-Analysis v4 ( Differences >0% favour the intervention. The GRADE assessment is moderate because of imprecision due to being a single study.

Resource Bundle

How to Cite

Citation: Treweek S, Bruhn H, Gardner H. Evidence pack Recruitment: Text messaging #2: quotes from participants (ID Rec7), 2021,

More Information

  1. This summary is from the Cochrane review of strategies to improve recruitment in randomised trials (
  2. It was prepared with financial support from Evidence Synthesis Ireland.
  3. The ‘Does it work?’ statement is structured according to effect size and GRADE certainty as per GRADE Guidelines 26 ( The statement is for a small important effect size and GRADE moderate certainty.
  4. The recommendation statement is the consensus view of the authors of this summary based on the GRADE certainty and features of the trials contributing to the evidence.
  5. If you have any questions contact
v1.0 - 22/12/2021
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