I see questions like this a lot: http://moz.com/community/q/webmaster-tools-vs-google-trends-data-doesn-t-add-up – people are wondering if Webmaster Tools Average Position Data is wrong or accurate. The issue is, you can not look at it the same way as rankings. In this video I explain the differences between webmaster tools average position and rankings. There’s some actionable tips for how to use each metric.
Great post by Jason Acidre
Google Webmaster Tools
The Ultimate List Of Rank Trackers
Moz Ranker Tracker
Wistia – Getting Loose On Camera
And also, Google’s Documentation on The Search Queries Report;