Management
RECRUITMENT
The management procedure is shown in In an attempt to mitigate against participant deception, the mention of the financial compensation was removed from social media advertising (Figure S2 in When we spoke to a genuine participant (whose name matched the person we reached on the phone), we explained we had called to confirm the details provided, and they remained in the study. From December 2020 onward, a percentage of participants were called at random each month to verify their details.In March 2021, we amended the social media advertising to reinclude the mention of the financial compensation but reduce the prominence of the financial compensation available, in addition to targeting Facebook advertising so it could only be viewed by males to try and achieve a more representative sample. This compromise was a balance between reducing the rate of participant deception and minimizing the impact on genuine recruitment, leading to a fall in the rate of manual participant deception. The advertising had specific parameters in terms of who it was displayed to at this time, which reduced the audience it was displayed to on Facebook. This second advertisement, which ran on social media for 90 days, was replaced by a final edit (Figure S3 in The other method we employed was an additional attention check on the baseline survey. One had been placed in the survey initially, a question: “Just checking that you are a human, please select ‘weekly’ as your answer to this question”. If they did not, they were screened out (62/7300, 0.8%). To further protect against manual deception, in November 2020, a second check was added, asking participants to enter their age, then, after a few further blocks of questions, to enter their age again. If these responses did not match, the participants were screened out (135/7300, 1.85%).One of the difficulties during this process was balancing the need to recruit large numbers of participants to detect small but meaningful effects while avoiding encouraging many attempts at fraud by making incentives too prominent. We were also mindful of trying to recruit a representative sample while also ensuring that participants were genuine. We were fortunate to have the support of NHS Digital in placing an advertisement (At each stage, a problem was identified, the core research team discussed the issue and how best to resolve it, and these decisions were checked with the full trial team, the Data Monitoring and Trial Steering Committees. The approach was flexible and reactive, depending on how the problem manifested. The decisions described in the case study were made on the basis of inclusion, with participants included in the study unless we could confirm that there was participant deception. Despite the issues experienced, the iDEAS trial successfully recruited participants to time and target.