Hello!



I'm looking to design security features for a large survey distributed via anonymous link with URL-set embedded variables (SchoolID) and (ClassID) that uses a unique identifier to prevent repeat survey takers. Here is where things get tricky -- some of the devices may be used by multiple survey takers via school computer labs using the same login information, so we can't use a straight "Prevent Ballot Box Stuffing" function. However, we will have unique URLs containing specific Class IDs, so I created an embedded variable using java which is a concatenation of the SchoolID, ClassID, and IP Address called ipID.



Is there any way to use ipID as a unique identifier to prevent a student from using the same URL on the same computer from taking the survey multiple times, but will allow another student to take the survey using a different URL? I was thinking this may involve creating a "contact list" of these unique identifiers using the "import from survey" option and then adding an authenticator in survey flow, in but this has not been successful.



Unfortunately we have to be able to prevent students from taking the survey twice, rather than writing SPSS syntax that identifies duplicates of ipID and having to decide which (if any) responses are valid.



Thanks!