The DuckDuckGo blog:

Private browsing mode and being logged out of Google offered very little filter bubble protection. These tactics simply do not provide the anonymity most people expect. In fact, it’s simply not possible to use Google search and avoid its filter bubble.

Ultimately:

We often hear of confusion that private browsing mode enables anonymity on the web, but this finding demonstrates that Google tailors search results regardless of browsing mode. People should not be lulled into a false sense of security that so-called “incognito” mode makes them anonymous.

If the average person knew this, and accepted it, they’d shit a brick. The. Switch to DuckDuckGo which is far superior.