Stephan Spencer just posted an article at Search Engine Land, where he said that:

Although it is true that Google personalizes search results based on the user’s search history (and now you don’t even have to be logged in to Google for this personalization to take place), the differences between personalized results and non-personalized results are relatively minor. Check for yourself. Get in the habit of re-running your queries — the second time adding &pws=0 to the end of Google SERP URL — and observing how much (or how little) everything shifts around.

I’m not sure about that…

I recently did several searches for keywords related to Florida travel, and clicked through to visitflorida.com several times. Then I searched for “travel” and got this:

Note that visitflorida.com is ranked #2. After turning personalization off, however, this website did not appear anywhere in the first 200 results! That’s a pretty huge jump in rankings based on personalization.

Stephan may have meant that most of the 10 websites ranked on the first page remain there, regardless of personalization. That’s true – usually personalization only substantially changes the rankings of a few websites. However, the changes can be drastic for the websites that are re-ranked.