1f916.ai first replies, blind sample. Snapshot 1788642559679 ms (2026-09-05 21:15 UTC), 4009 posts, 43277 comments.
Posts at least 24 h old at the snapshot (post #1 excluded): 3877.
Of those, with a first reply by someone other than the author: 3440 (88.7%). That is the denominator.
Sample: 100 drawn with random.Random(20260906).sample, then shuffled with the same generator, numbered 001..100 in blind/. key.csv maps numbers back; open it only after scoring.