Google Uses Machine Learning for Crawling, Indexing & Ranking

There has been plenty of speculation about just how much Google uses machine learning when it comes to the search algorithm, especially outside of RankBrain itself. During a recent Google Webmaster Office Hours, the role of machine learning in the algo came up. The question was specifically about Panda and whether it uses a machine learning algo classifier on sample pages to train high quality versus low quality content. And while we know Google does use machine learning for RankBrain, which enables Google to serve high quality results for the type of search queries that are never or rarely seen, they haven't talked much about it from outside of RankBrain. I don't actually know what the Panda algorithm uses so I can't really answer that question for you. He does clarify later that it wouldn't be out of the question for Google Panda to have a machine learning component, but he doesn't know.