Evidence Summary
What is it?
As follow-up participants receive a handwritten or printed post-it note either alone or with usual follow-up or a newsletter. The note contains text such as “Please take a few minutes to complete this for us. Thank you.”
Does it work?
Addition of a post‐it note may result in little or no difference to retention.
How big is the effect?
An increase of 0% (95% confidence interval = -1% to 1%).
How certain are we?
GRADE Low certainty.
Recommendation
We recommend that trialists add post-it notes to follow-up in the context of an intervention evaluation.
How can I use this straight away?
See Resource bundle below for support materials.
Practical Impact
Imagine initial retention is 65% of those approached. You have a trial with 100 participants that needs responses from 80 to meet its statistical power calculations. Retention of 65% means that you will be 15 responses short (see chart below).
Now imagine adding post-it notes to follow-up. The chart below shows the impact of an absolute increase of 0% (95% CI = -1% to 1%). Retention remains unchanged.
Cumulative Meta-Analysis*

*Random effects model done using Comprehensive Meta-Analysis v4 (www.meta-analysis.com).
Differences >0% favour the intervention. The GRADE assessment is low because of imprecision.
Resource Bundle
How to Cite
Citation: Ostrovska B. Evidence pack– Retention: Post-it note (RET17), 2023, https://www.trialforge.org/retention-sector/post-it-note-id-ret17/.
More Information
- This summary is from the Cochrane review of strategies to improve retention in randomised trials (https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.MR000032.pub3/full).
- The ‘Does it work?’ statement is structured according to effect size and GRADE certainty as per GRADE Guidelines 26 (https://doi.org/10.1016/j.jclinepi.2019.10.014). The statement is for trivial, small unimportant effect or no effect and Low GRADE certainty.
- 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.
- If you have any questions contact info@trialforge.org.