What is it?
A pen sent with trial questionnaire and/or study materials, which serves as a reminder to return study items. The pen can contain the research institution details and/or the trial name and logo
Does it work?
Addition of a pen may increase retention slightly.
How big is the effect?
An increase of 2% (95% confidence interval = 0% to 4%).
How certain are we?
GRADE Low certainty.
We recommend that trialists consider adding a pen to invitation packs or questionnaires.
How can I use this straight away?
See Resource bundle below for support materials
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 including a pen with study materials. The chart below shows the impact of an absolute increase of 2% (95% CI = 0% to 4%). Retention is now 67%, which means our best estimate is that you would now only be 13 responses short.
How to Cite
Citation: Clark L, Coleman E, Arundel C, Doherty L, Torgerson D. Evidence pack– Retention: Including a pen with study materials (Ret3), 2020, https://www.trialforge.org/retention-sector/including-a-pen-with-study-materials/
- The majority of the data in this summary is from the PROMETHEUS project (https://www.york.ac.uk/healthsciences/research/trials/research/swats/prometheus/).
- 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 small effect size 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 email@example.com.