Why? OVT 1800, WT 11,000/20,000

[MeanerDomainer]

Wordtracker much higher than Overture. WHY? HOW?

Checking the same term, I got
OVT 1,800
Word Tracker 11,000/20,000
(The terms are not seasonal or recently in the news, so that could not account for the difference. I know that people definitely search for this.)
Is it possible that OVT is off that much?
Can WT be manipulated? How easily?
I have seen one one example where an unregistered .com was showing WT 2100/4000, but it is now down to 130/235. (Only about a week has elapsed and the item is not seasonal/headline topic.) What is likely to cause such a difference?
Thanks!

 

[Ronald Regging]

You also have to remember that OVT is defunct.. It hasn't been updated in months and probably never will be again.