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Internet-based electronic data collection (ID REC19)

Evidence Summary

What is it?

Instead of using a paper system, participant data collection is done via the internet.

Does it work?

Internet‐based, electronic data collection compared to paper‐based may reduce recruitment.

How big is the effect?

A decrease of -13% (95% confidence interval = -24% to -3%).

How certain are we?

GRADE Low certainty.


We recommend that trialists use internet-based electronic data collection in the context of an intervention evaluation.

How can I use this straight away?

See Resource bundle below for details on how to use internet-based electronic data collection.

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 using internet-based electronic data collection. The chart below shows the impact of an absolute decrease of -13% (95% CI = -24% to -3%). Recruitment is now 17%, which means our best estimate is that 176 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 low because of the imprecision of a single study.

Resource Bundle

How to Cite

Citation: Ostrovska B., Evidence pack­– Recruitment: Internet-based electronic data collection (REC19), 2023,

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 large effect size and GRADE Low 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
v2.0 - 10/07/2023
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