David Coleman: Depends on what kind of action google take against you-could be manual penalty, algorithmic e.g. panda, penguin in which case rankings might slip or maybe just a PR drop.
Tony McCreath: We only see the toolbar pagerank which is not an accurate representation of the true PR. my question would be: does this visible pagerank get changed with penaties or algorythms outside the PR algo itself.
PageRank (assuming you meant one word and not your page's rank) would only be affected if it's related to links (as that is what PageRank measures, but there have been exceptions), and even then it may not if it is a manual penalty. Furthermore, PageRank (Toolbar PageRank) only gets updated infrequently, so infrequently that you could be penalized, get fixed, recover, and the Toolbar PageRank would still not have updated.
Jim Munro: Interesting. We sometimes encounter people who buy a high PR site only to find later that it's a toxic domain so I would say that in at least some cases that losing page ranking does not always coincide with losing PageRank.
Edwin Jonk: From the expert panel in this weeks SEO Questions hangout on air on 01:37:27 into the YouTube video:
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