> "a bunch of people have guessed my email address and emailed me saying, 'I heard that you’re doing this. I’ll be in the control group just because I think thi

> "a bunch of people have guessed my email address and emailed me saying, 'I heard that you’re doing this. I’ll be in the control group just because I think this is important. I don’t need any compensation, I just believe in this idea, and I want to be part of the study.'" This is hardly evidence that getting 2,000 control volunteers will be easy. Unlikely that the people who knew about the study and came forward are representative of the entire target test group on relevant criteria (e.g. income level). It's great to see support for the experiment and getting people to volunteer information without receiving money is a solvable problem, this answer just seemed evasive and promotional when a "you're right, it's going to be tough and we're working on it" would have been plenty justified.