Douglas took a survey on dill pickles. He was asked questions about what he liked and disliked about dill pickles, when and where he usually ate the pickles, and to list and rate all the brands of dill pickles that he could recall. He was asked his opinion on packaging and on the characteristic taste of the pickles, and what he disliked about all these aspects. The survey was conducted by an ad agency to help develop a creative strategy for dill pickles. If there were several people surveyed besides Douglas, we can assume he was participating in a(n) study