Telephone Checks
To further avoid the likelihood of including fraudulent entries, every participant who enrolled before the CAPTCHA had been added was contacted by phone. A participant was classified as a bot if either (1) the number provided was false or (2) it was confirmed the participant was not known at that number.To minimize bias in removing participants after randomization, decisions erred on the side of inclusion, and unless there was proof that participants were not real, they remained in the study. For example, a participant remained in the study even if nobody answered the phone after 2 attempts. An additional 121 bots were identified and emailed as before, allowing 24 hours to respond with verified contact information.