Would any of you be able to help with this Qualtrics question: I have been trying to do multiple anonymous link types (so that I can see in each anonymous participant segment, how many responded) using the following method—I take the anonymous URL link, and then I add ?source=researchers to it. This is supposed to create a variable in the dataset called source and assign the 'researchers' value to that respondent. But no matter what I do when testing it, the variable is blank. 
Have any of you done this previously and do you have any leads?