The author's views are entirely his or her own (excluding the unlikely event of hypnosis) and may not always reflect the views of Moz.
Does Google use engagement signals to rank web pages?
Exactly how Google uses engagement signals (i.e. clicks and interaction data) is subject to endless SEO debate. The passage above suggests Google uses engagement metrics to train their machine learning models. Google has also admitted to using click signals for both search personalization and evaluating new algorithms.
While many Googlers no doubt work hard to be helpful to the SEO community, they are also under pressure "not to reveal too much detail" about their algorithms out of caution that SEOs will game search results. In reality, Google is never going to tell SEO exactly how they use engagement metrics, no matter how many times we ask.
Most SEO debate focuses on if Google uses organic Click-through Rates (CTR) in its ranking algorithms. If you are interested, AJ Kohn's piece is particularly outstanding as well as Rand Fishkin's Whiteboard Friday on covering this topic. For a nuanced counter-view, I'd recommend reading this excellent post by Dan Taylor.
To be fair, I believe most of the debate around CTR up to this point has likely been far too simple. Whatever way SEOs think Google uses click data, how