Receptional_Andy - 7:45 pm on Nov 11, 2009 (gmt 0)

Which is more accurate is a statistical question, which needs a bit more information.

Google's tool has a much bigger and more reliable dataset, since Google have the biggest database of search keywords. If you're going to trust one tool, use the one with the biggest dataset.

That said, every keyword tool processes the numbers before they provide them to you, which means that for some cases, a smaller dataset with different processing could give you a more reliable answer - long tail searches, for instance.

One key problem with Google's tool is that it's designed to give advertisers an idea of how many eyeballs their ad is likely to get. So, it includes things like impression data on the content network which heavily bias generic keywords.