What is the Predicted Daily Searches and how is that calculated?

Not too long ago, WordTracker released their formulation on a Predicted Daily figure which they indicate as follows:

Number of times
keyword appears in
our database
———————-
Total number of
keywords in our
database

Estimated total number of
daily queries on all search
engines*

Estimated daily
volume of searches
for the keyword

So for a keyword that appears 9,000 times in our database, this is the number of daily searches that we predict:

9,000
————-
323.4 million

570.4 million*

15,873 daily searches

* Every day, on average, we collect about 3.59 million search terms from Dogpile.com and Metacrawler.com, who according to Netapplications.com account for 0.63% of searches across all engines. By combining these two figures, we estimate that the total daily searches across all engines is 570.4 million."

With that in mind, all WordTracker data will have the Predicted Daily figure that is shown in Global, across Google, MSN and Yahoo given their respective marketshare in the global search scheme.