Payment for research participation can raise ethical concerns and legal issues. But it can also raise scientific problems if it causes participants to lie about their eligibility or other things, like adverse events.
In our new study in JAMA Network Open, my colleagues and I wanted to see whether payment causes deception about study eligibility, and if so, whether more payment results in more deception. We found the answer to the first question was yes – but contrary to what one might expect, payment amount didn’t matter.
It’s hard to study if people are lying, for obvious reasons. To get around that problem, we created a randomized controlled survey experiment conducted via GfK KnowledgeNetworks with a nationally representative sample of U.S. adults. We told our control group they were eligible to participate and receive five dollars if they ever had a vaccine in their lifetime (we expected nearly everyone to say yes, and they did). Then, we asked the control group if they had a recent flu shot. Because their eligibility didn’t depend on recent flu vaccination, they had no reason to lie about that.
We also told three experimental arms (A groups) they were eligible to participate and receive five dollars, 10 dollars, or 20 dollars respectively if they had a recent flu vaccine and 3 more arms (B groups) they were eligible if they had not had a recent flu vaccine. Then we asked them if they had a recent flu shot. Of course, these groups had an incentive to lie because their payment might depend on it.
If no one was lying, A and B groups should have reported the same rates of flu vaccination as the control group and as one another. But that’s not what happened.
To read what we found, check out the original post, which appeared on the HEALTH Policy$ense blog.