Association Between Financial Incentives and Participant Deception About Study Eligibility

Abstract

Importance: Offers of payment for research participation are ubiquitous but may lead prospective participants to deceive about eligibility, jeopardizing study integrity and participant protection. To date, neither the rate of payment-induced deception nor the influence of payment amount has been systematically studied in a nationally representative randomized survey experiment.

Objectives: To estimate payment-associated deception about eligibility for an online survey and to assess whether there is an association between payment amount and deception frequency.

Design, setting, and participants: Randomized, 7-group survey experiment. Data were collected in March 2018 and analyzed from March to August 2018. The setting was a nationally representative online survey among US adults drawn from the GfK KnowledgePanel.

Interventions: Varying payment amounts for participation ($5, $10, or $20 cash equivalent) and direction of eligibility criterion (having received or not having received an influenza vaccination in the past 6 months).

Main outcomes and measures: Proportion of respondents reporting recent influenza vaccination.

Results: In total, 2275 individuals participated in the survey, a 59.4% (2275 of 3829) response rate; 51.8% (1108) were female, and 21.1% of respondents (399) were aged 18 to 29 years, 24.9% (532) were aged 30 to 44 years, 26.0% (601) were aged 45 to 59 years, and 28.0% (738) were 60 years or older. For participants offered a $5 incentive, the reported frequency of recent influenza vaccination was 16.6% higher (95% CI, 9.1%-24.1%) among those told that eligibility (and thus payment) required recent vaccination than among those told that eligibility required no recent vaccination. The corresponding differences were 21.0% (95% CI, 13.5%-28.5%) among those offered $10 and 15.4% (95% CI, 7.8%-23.0%) among those offered $20. Estimated proportions of ineligible individuals who responded deceptively regarding eligibility ranged from 10.5% to 22.8% across study groups. There was no evidence that higher payment was associated with higher frequency of deception.

Conclusions and relevance: In a nationally representative randomized survey experiment to evaluate whether and to what extent payment is associated with participants misleading investigators about their research eligibility, this study found evidence of significant deception. However, no association was observed between payment amount and frequency of deception. Further research is needed to extend these findings to clinical research. These data suggest that, when possible, investigators should rely on objective tests of eligibility rather than self-report.

Figure.. Percentage of Respondents Reporting Influenza Vaccination in the Previous 6 Months

Bars show the percentages of respondents in each group who self-reported that they had received an influenza vaccine in the previous 6 months. Respondents in group 1 had no financial incentive to respond affirmatively or negatively to the question about recent influenza vaccination; the dashed line indicates the group 1 rate of reported recent influenza vaccination, which should be the same across all study groups in the absence of deception about eligibility in A and B groups. Respondents in groups 2A, 3A, and 4A had a financial incentive to respond that they had received a recent influenza vaccine. Respondents in groups 2B, 3B, and 4B had a financial incentive to respond that they had not received a recent influenza vaccine. P values for the 7-way comparison and for all 2-way comparisons between A groups and B groups were less than .001, indicating statistically significant levels of deception in the intervention groups. In contrast, the P value for the 3-way comparison across the A groups was .81 and across the B groups was .75, providing no statistically significant evidence of dose response based on increasing payment amount.