galapiat - 6:58 am on Apr 19, 2013 (gmt 0)
On my site I have noticed that CTR increased dramatically and CPC went downhill for clicks coming from the US, and mainly from mobile devices. This started end of march.
Seems that a lot of webmasters are experiencing the same problem, looking at the AdSense Products Forums:
Google doesn't seem to be doing anything about the problem except closing accounts.
Anyone care to comment?