Most recently at https://astralcodexten.substack.com/p/nootropics-survey-2020-results https://astralcodexten.substack.com/p/nootropics-survey-2020... Note that

Most recently at https://astralcodexten.substack.com/p/nootropics-survey-2020-results https://astralcodexten.substack.com/p/nootropics-survey-2020... Note that he's switched to a different URL for his blog; that may be why you couldn't find it -- although I'm pretty sure he mentioned it on the old site several times as well.