Forum Moderators: Robert Charlton & goodroi
However, there's no doubt that Google does watch the organic results for which item gets clicked. But in the organic results there's no way for a search engine to know if the click resulted in a purchase. That's why I assume you are asking about Adwords CTR.
Otherwise Google has no access to the browser at the critical moment. The only way that happens is when a site is using Google to track Adwords conversions. And even then, as far as I can tell, they are looking for a specific Adwords cookie that was placed when the ad was clicked, and not a general Google cookie.
Now I suppose the Google Toolbar might be able to report when the user goes to any shopping cart page or sales confirmation page -- but that would be extremely intrusive, and (dare I say) just a touch evil in my book.
I don't think this approach, even if possible technically, is something that Google would persue within the organic results. Google wants to know if their results gave a page that satisfied the user --- one that was relevant to the search. There are many types of relevancy for searches and only some kinds of relevancy would result in a sale.
One thing Google can watch easily is if, after one click, the searcher comes right back to the organic results page and clicks on a different page. If that happens a lot, then Google might decide that their algorithm needs some tweaking. But I still don't think they would directly make any change to how that one particular page is ranked for that search. Such an approach just wouldn't scale well, as far as I can see.