I used to do surveys for the Kellogg school of management elab at Northwestern University, and they let me know right away if I was not eligible. The main problem was that the surveys filled up fast, and if I waited a day to sign up for a survey, I found out that they did not need any more people. Most of the surveys were chance drawings, with it usually being 1/25 chance or 1/50 chance. The surveys were easy, and I won a $25 and a $50 Amazon GC from them. I don't know why I quit doing them. I just checked and they are still doing them. I might sign up again to do them. I live two miles from their campus, and so I am very comfortable with doing them.