Exactly, Wordtracker gets their results from DogPile while Overture gets their results from Overture (The Overture database is seperate from Yahoo!, even though Overture is owned and operated by Yahoo!).
In addition to the difference in processing queries, the Overture database can become inflated by SEOs researching keywords. This is why you will occasionally see a long-tail outpace a short-tail.
The trick, so to speak, is to not look at the numbers in their raw form but to compare results against results within the same database to uncover trends and to validate those trends by comparing Wordtracker and Overture against each other.
After uncovering the snapshot trends (Call it the X-axis) you can add progress over time (the Y-axis) by looking at Google Trends. Once again, you may have to make some assumptions. For example, belly dancing waist chain may not show-up while belly dancing does. You can probably apply the trend line from belly dancing to belly dancing waist chain and even reach a greater level of confidence by looking-up other shorter-tail belly dancing related terms and checking to see if their trend lines are similar.
The reality is that finding-out whether or not a search term garners enough queries to be worthwhile if fairly easy. The hard part is to then look at the rankings and determine what it will take to get in there. This is where too many fall short. They either become disuaded by the competition too quickly or they attempt to rank for key phrases that are too far out of reach from their domains' current off-site optimization strength.
Last edited by 211Club; 26th June 2006 at 11:03 PM.