I would like to limit a group of MTURK HITs such that if a worker has taken any previous HIT included in the group, he or she cannot take any future hits included in the group.
I have seen two distinct methods of doing this described here on StackOverflow.
Use qualifications. https://stackoverflow.com/a/16415447/364966
Have the HIT check with a function on your server and if a worker has taken a previous HIT from the group, politely inform the worker that the hit won't be available. https://stackoverflow.com/a/3782847/364966 and https://stackoverflow.com/a/13851920/364966
One poster on StackOverflow commented that "I used to do this with qualifications, but found that it really limited participation." https://stackoverflow.com/a/3782847/364966
Is it better to use method #1 or method #2? Or, are both methods equally viable?