Professor Guerra is writing a research proposal to examine the extent to which college students are victims of "RFID skimming", where an individual can use a device to read one's debit$/$credit card from a distance and use that information for their own purchases.

He thinks he should look at several individual characteristics of the students he is going to study. What variables and subsequent attributes would you suggest he study? List $4$ variables and how they would be operationalized.