Google has changed the way it handles search for signed-in users which now prevents you from seeing their referral keywords in google analytics. The third most common keyword in my analytics data now is 'Not Provided' which means that google has encrypted the search query for users of google+ or who have signed in to their google account.

This new feature appeared a week ago, and was announced in this Google blog post. Although CPC search data is not affected, the masking of referring keywords is going to cause some headaches. At present, it only represents a small percentage of organic search, but as google+ is pushed on to more and more users, the 'not provided' token will become a much more prominent figure in search analytics. Although Google are pushing this as a 'privacy feature' I personally think that it is an unintended consequence of using https to perform searches. When you use https, the referrer is blocked by most browsers, and it's difficult to get round this without significant work.

Judging by the comments beneath the google post, most people seem to feel the same way that I do, that it's a really bad idea, and can only serve to make things harder for SEO teams.

What a lot of people in the comments don't seem to realise is that Google didn't intentially block the referral data, but it's a side effect of using https to perform search - https blocks referring keywords when visiting your site. changing to a different analytics type service, or even using weblog based stats programs will do nothing to change that. The only way round this is for Google to stop using https for search as default- personally, I dont really care whether I'm using https or http for search, I've got nothing to hide, but I can see some situations where having the option would be useful (eg in China). I think the https search should be an opt-in facility for logged in users, not a default.

Having said that, it is possible for google to track clickthroughs on their end and attach those to webmaster tools data, which does not use website hosted javascript based data collection methods.

Wish I'd have known about this a few weeks ago, I would have registered notprovided.com which is currently up for sale for $1,000,000.