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Hi there, Since Domain Authority is a Moz metric, it is not affected by CTR due to Moz not being able to determine or collect this sort of data. As far as CTR and PPC influencing search rankings goes, there are good reasons why Google would not rely on either metric too intently. For one, it would be very easy to mimic a very bad bounce rate on a competitor's site: set bots to click on search results to a competitor website, click straight out. It would be a big conflict of interest for PPC to influence SEO either positively or negatively, and although none of us are naive enough to believe that Google always does everything with the best of intentions, they would be in a world of trouble if this type of behaviour were proven. CTR and bounce rate are so easily influenced / manipulated by factors outside of quality, authority and relevancy that I assume their influence on rankings is quite low. Sure, this data is valuable to Google, but it won't be a signal that has a huge amount of relevance.

Rob's advice is very good in regard to sending people to the more effective inner page. I would not mess around with canonical tags, unless the content is actually duplicated.  Rethinking your internal links might be helpful.  One thing I have done in similar situations is to use a keyword anchored link from the category page to the home page.  Moz Analytics will tell you this is keyword cannibalization, but it does often work to nudge Google toward ranking the home page.  So on a page about "Red Widgets", you could link to the home page with "Red Widget Company".  What is likely to happen is that you will sort of split the searches based on user intent, and searches that are more than just the base keyword. Searches that Google thinks are more informational would go to the Red Widgets page, where someone looking for a supplier or maker of red widgets might be sent to the home page.  Similar links throughout the site where they are appropriate would also be good.  Like, if you have a page or a blog post that mentions red widgets, link to the category. If it says something about manufacturer of red widgets, link to the home page.  Just like incoming links, you don't want to overuse the same keywords, though.  Mix things up a bit within the same topical theme (red widget maker, manufacturer of red widgets, red widget company...)