Is there a preference between "in" and "among" in the following sentence?
The data consist of test scores collected in/among students participating in an international survey.
"Among" is more appropriate than "in" in this context. I'd go do far as to day that "in" is entirely the wrong word to use here.
"From" may be even more appropriate if the data are being collected from all members of the subject group rather than from only a portion.
To my ears:
sounds very odd.
This would indicate that only some of the students taking the survey are the source of data.
This is what I believe you intend to say, that the data were collected from the entire group of students who took the survey.