I'm going to have to strongly disagree with at least the "useful" adjective in this statement. I would concur that if the click-through-rate and impression data were accurate or consistent with other data sources that claim to show the same thing (Google Analytics, log file analysis, Google AdWords campaigns) it would be phenomenally valuable.<p>However, as it stands, my digging suggests that not only are the numbers dramatically different between other sources and GWMT, they're not even consistently different (at times, the multiples of variance can range from 0.5X-3X).<p>A number of good posts have been written on this by the webmaster/SEO community already:<p><a href="http://www.distilled.co.uk/blog/seo/new-google-webmaster-tools-keyphrase-data-is-70-useless/" rel="nofollow">http://www.distilled.co.uk/blog/seo/new-google-webmaster-too...</a><p><a href="http://www.davidnaylor.co.uk/google-webmaster-tools-2.html" rel="nofollow">http://www.davidnaylor.co.uk/google-webmaster-tools-2.html</a>
Compared to Google Analytics (which by necessity undercounts queries, due to Javascript-related issues) this undereports my queries by a factor of two.<p>Line-by-line comparisons seem to hold up pretty decently, though, in my five minute spot-check.
Can anyone beat my record for worst keyword clickthrough rate?<p>0.01% (12 clicks out of 110000 impressions)<p><a href="http://i43.tinypic.com/156ppuw.png" rel="nofollow">http://i43.tinypic.com/156ppuw.png</a>