Reading your recruitment funnel: what each stage actually tells you

A study’s recruitment funnel -- invited, accepted, screened, qualified, scheduled, completed -- looks like a simple shrinking bar chart, but each transition is telling you something different, and conflating them leads to the wrong fix.

A big drop between invited and accepted usually points at the invitation itself: the opportunity wasn’t compelling, wasn’t well-targeted, or reached the wrong people in the first place. That’s a targeting or messaging problem, not a study-design problem.

A drop between screened and qualified is a different signal entirely -- it means your eligibility requirements are filtering out a meaningful share of the people who were otherwise willing to participate. Sometimes that’s correct and expected. Sometimes it means a requirement is stricter than the research question actually needs.

A drop between qualified and scheduled or completed often has nothing to do with recruitment at all -- it’s usually about the logistics of actually taking part: timing, effort, or friction in the study itself.

Treating the whole funnel as one undifferentiated leak is how teams end up "fixing" the wrong stage. The stage where people are dropping off tells you which part of the process to look at first.