Last year, Google decided to start creating ‘private’ searches; basically automatically removing search result information from all logged in users. At first, they stated that it’d only affect about 2% of your visitors – a small number.
These days, they take up 28% of our visitors from Google Search.
Why does this matter? Well, more information is better. But worst, it made Y-o-Y comparisons much more difficult. After all, 28% of all visitors are being ‘wiped’ from our results – but there’s no way of knowing which results they were wiped from, so it could be 100% of these visitors from a search results to 5% or something.
It’s worth keeping an eye on and better yet, keeping an eye on the rate that this increases.
And if you want a workaround (work being the emphasis here); keyword data is still being given to Advertisers; so log in to your Google Adwords account.