Many advertisers have been complaining about the accuracy of the Google Keyword Tool. We have complaints specific to the counts showing different results based on being logged in or out.
But now we have a Google AdWords Help thread with confirmation from a Googler about at least one or two keywords being reported inaccurately.
The advertiser said:
I have done a checking in two different period of times - one today and one about a month ago. I am getting now completely different results from what I got a month ago: Market - Germany, Language - GermanI realize there can be changes in the numbers, but this is too radical to make sense.
Google Keyword Tool Engineer, Scott, said:
Thank you for the heads up on this issue. I'm seeing the same thing internally for those particular keywords and have passed on the details to the rest of the dev team. I'll post back here once we find out more.
So Google is now admitting to an issue so maybe other issues will be found when they debug this?
Forum discussion at Google AdWords Help.

Comments:
cheap online shopping
02/24/2011 06:50 pm
Issues can be raised anytime anywhere. We know that there are human beings who are running Google. And from human beings mistakes and error can be generated anytime. Its good to know that Google admit that there is issue. Thanks
Morgan Rees
02/25/2011 02:13 am
Seriously? Google's Keyword Tool is wildly inaccurate. I thought that was pretty widely accepted
online shopping uk
02/25/2011 07:24 am
I have also noticed that Google keyword Tool Shows Different results during i was logged in and when i logged out it shows different results..
Carly
02/25/2011 09:16 am
Interesting development and response from Google. If we have been relying on it too heavily for keyword research, it could potentially be time wasted?
CloudhostingUK
02/25/2011 12:27 pm
But to run a web business and to get good traffic the only required thing to rely is Google.
Jim James
02/26/2011 01:00 pm
but we are still going to use google, just hope it will be solved. http://www.idnikeshoes.com/
SEO Company
03/01/2011 12:50 pm
Good topic! I think some time Google is wrong but Google have heavy data so forget to miner mistake and go with Google.
The Unablogger
03/02/2011 08:27 am
This is not a surprise to hear about this inaccuracy, but the engineer's response is perhaps a bit disingenuous, because Google has already announced publicly that they are now skewing the Keyword Tool results away from long- and mid-tail queries in favor of (what they deem) commercially viable keywords only. See this blog post from Oct 2010: http://bit.ly/euByPV