Perhaps this has been around for a little while now, but this is the first time I've noticed this:
Partial credit amount*: Will Depend on Time Spent on Qualifying Questions AND 1 entry into the European Getaway Sweepstakes as a token of our appreciation if your survey answers do not meet the criteria to fully qualify for the study OR if the predetermined number of participants has been reached.
Might be a step in the right direction...