It’s no more possible to identify the keywords used by visitors to access the sites searched, if they remain connected to their Google+ accounts.

In fact, users logged in Google+ are automatically redirected to the https version, for which the search engine doesn’t provide the search key used, that results as Not provided“. Consequently, when the user searches on Google being connected to Google+, the keywords used to find the web sites are no longer provided.

The “Not provided” key, that you can see in the report Referrers > Search keywords”, then indicates how many visits are generated by visitors who surf and search remaining logged into their Google+ accounts.

The figure for “not provided” key increased significantly since March 5th 2012, when Google has extended to the whole world, including Italy, the automatic redirect to https version for all logged in users to their services.
The inability to detect the keywords entered by users surfing while logged into Google+ impacts on all the web analytics tools on the market.

The chart shows the trend of the visits coming from Google with keyword “not provided”.  You can see very well the growth since March 5th.