So far, we've covered who to recruit, how to find participants, and what to inform them about. These steps will yield a list of potential study participants. Note that all of the information about the participants so far has been self-reported by the participant, and their claims have not been confirmed.
Re-screening by using means other than self-reporting may be desirable in some cases. It can be a tricky situation, because of both feasibility and the risk of damaging the rapport with the participants.
Re-screening on key profile aspects may not work if they are linked to habits or interests. If a key profile attribute is that coffee lovers drink more than four cups of coffee a day, on average, it is impossible to follow each of these participants as they go about their daily lives, in order to count the number of cups of coffee they consume.
If, on the other hand, participants must be existing customers of a particular utility provider, a copy of a statement...