| 8:29 am on Oct 20, 2011 (gmt 0)|
Has Google instant changed the predictive search, perhaps users are seeing what they want during the prediction, thus not going as far as searching the full search term. Also depending on industry, the time of year and day of week can have effects on search's.
| 8:33 am on Oct 20, 2011 (gmt 0)|
Are you logged in? Try some of the rank checking tools so that you can see what others are seeing, you might be surprised.
| 9:08 am on Oct 20, 2011 (gmt 0)|
That reminds me, another thing to try after you do a search click the options tab at the top right hand corner - click web history and make sure it says "Customisation based on signed-out search activity is disabled.
You do not need to be signed in or even have a G account to see diferent results if this is enabled.
| 11:45 am on Oct 20, 2011 (gmt 0)|
All search personalizations are turned off, just the raw results I am ranked number one. The search isn't seasonal so should always get a consistent number of searches.
| 11:56 am on Oct 20, 2011 (gmt 0)|
A couple of days after this date?
This may then be to do with the 'minor'/'very major' Panda update.
One of my sites is still ranking very well for previous top keywords on my homepage - but is referring zero traffic to the rest of the internals. Maybe this is what is happening to you too.
| 12:09 pm on Oct 20, 2011 (gmt 0)|
It's possible that while one of your pages (home page?) is still ranking for its targeted term, the other pages are no longer ranking for long tail search terms.
The long tail search can contribute more than half the traffic to a site, so if you lose that you will see a big drop in the visitor numbers.
You need to do some in-depth analysis of the before and after stats to see if a pattern emerges.
| 5:20 pm on Oct 20, 2011 (gmt 0)|
Happen to one of my sites, I'm ranked 1 for my main terms 3 or 4 and my long-tails are gone. I got a 75% drop in traffic....