What could cuase a sudden dramatic drop in CTR/clicks?

CRT/clicks suddenly drops to less then half overnite

[funandgames]

Clicks plummet 70% overnite April 15th. Never happened before. Impressions and traffic the same.

What could casue this if no changes to sites/channels are taking place? Stolen clicks? Advertiser dropping an ad that was relevent to the site topic? Change at Google? Bad report data? Any ideas? Anyone experienced a sudden drop in clicks lately?

[martinibuster]

Quality of the traffic
Check the "bounce rate" of your traffic. Bounce rate is the percentage of people who land on your website then bounce out after a couple seconds. This can indicate that the keywords bringing in traffic aren't relevant for your website

Despite geotargetting issues, try to check your ad relevance.

Additionally, I'm wondering if "depth of content" has something to do with G's new adsense algo, as well as links.

[funandgames]

Thanks for the tip. I doubt bounce traffic would change 70% overnite though. Has anyone else experienced a sudden abrupt drop in CTR?

[europeforvisitors]

My CTR dropped noticeably on April 4 and hasn't recovered. Nothing as drastic as a 70-percent drop, though--more in the range of 12 to 25 percent, depending on the day.