I'm surprised there isn't much discussion on this one. This is above and beyond what folks have been discussing to date. There have been significant increases in "Not Provided" stats starting on Oct 30, 2011. I've had 10+ people confirm on Twitter and there are plenty of screenshots floating around depicting the increase. It is rather significant. This is not the measly increase we first saw when it was announced.
On one site I monitor, we were averaging about 500 per day. That jumped to 1,700 on Oct 31, 2011 and it then jumped to 4,200 on Nov 01, 2011 and appears it will be in the same range if not more once Nov 02, 2011 closes. Similar spikes are being seen by quite a few folks.
I hit 19% yesterday. If the trend continues, I'm going to look at phasing in alternative analytics so I can compare an another solution with Google Analytics while data from the later is still largely available.
Given the lax response on this, I kind of feel like I'm over overreacting -- but in a case like this, I'd rather be safe than sorry.
For some clients I've been seeing the number creep north of 20% (this for the last 7 days, i.e., 11/7 to 11/13). Not happy at all, but I think we're fairly helpless on this one...at least until Google starts getting more heat from Federal government inquiries into its monopolistic practices, at which point this issue should start getting more sunlight (i.e., "Protecting privacy? Really? Like you DON'T do for visitors clicking through paid ads?")
We've noticed an increase in (not provided) on most of the websites we track. Even more strange though is that one of our client sites do not have even one instance of (not provided) though we do show (not set). I find it hard to believe that not one person coming to the site is logged into Google. Any ideas?