Robin is a frequent publisher of articles on Search Engine Optimization and provides technical support to Wordtracker.In her findings she concluded on a single keyword the searches produced by the Overture search engine were 10 times that of Wordtracker.
As the number of keyword's in a phrase increase so do the number of variations of the expression. So on a 1 keyword you may have 5 possibilities, on a 2 keyword group around 16 and on a 3 keyword group around 50 depending on the phrase. It's not a mathematical permutation, as not all combinations of words make sense in English. The Wordtracker net, how does its size affect the catch. For example if the Overture search engine network is larger, it means there's a greater chance of catching more searches than Wordtracker through its network.So just how big's the Overture search engine 'Net' ? Published figures seem scarce, but it's certainly got a lot bigger since it became part of Yahoo's network. In the random selection of the keyword expression "child toy", a query on Google produced a total of 14,397 web pages using the 94 keyword group combinations tested. Google stated the size of their database to be 4,285 million pages, so what was found represents 0.000336% of their total database. A similar query on MSN produced 6,105 web pages using the 94 keyword groups and on the Overture search engine it produced 2,979 pages. If the number of pages found on the Overture search engine & MSN databases reflect the size of the database it could imply using the Google figure, the Overture search engine has a database of 2,979÷0.00000336 or 887 million pages. Overture's search engine database is 2.7 times larger than Wordtracker's.
The Overture search engine is certainly a major player with a very large affiliated network to which it provides searches and PPC services. Does this mean the Overture search engine has more reach than Wordtracker and a larger database & network to obtain searches ?...Quite definitely Without doubt the number of search returns by the Overture search engine are more than Wordtracker since they contain variations of the keyword or expression. If the Overture search engine database is larger than Wordtracker's, this indicates a larger network to get searches. Then it will also produce more searches on the same keyword's in a given time than will Wordtracker. If a single keyword has 5 possible variations this does not mean it will generate 5 times as many queries. From a statistical viewpoint around 95% of the traffic is likely to come from 4 out of the 5 keyword variations.
So for a single keyword if the Overture search engine gives 4 times as many returns because it includes all variations and 2.7 times the returns due to its larger size that's 4 x 2.7 or 10.8 times what Wordtracker gives for a single keyword. In Robin Nobles report she arrived at a multiplier of 10 on a single keyword example by an entirely different means. It shows good agreement with my multiplier of 10.8. From my findings, on a two keyword phrase, results indicate 8 combinations can account for about 95% of the Overture search engine searches. So that's 8 x 2.7 or 22 times the search results for Wordtracker. It agrees fairly well with the average multiplying figure of 21, obtained on a two keyword search in this evaluation. With a 3 keyword phrase around 12 combinations can account for 95% of the traffic. On the Overture search engine that's 12 x 2.7 or 32 times the returns for Wordtracker. These rough guides depend on the actual keyword phrase as to how many combinations of words are likely in a search, so the multiplying factors can be different.
So which keyword analyzer do you believe ? I suggest the answer is somewhere in between Wordtracker & Adword Analyzer.Based on this evaluation the Wordtracker estimates of traffic could be on the low side, by a possible factor of 2.7. Adword Analyzer ( or Niche Finder ) is likely on the high side by a factor of 4 to 12. This depends on whether you're looking at single keyword or three keyword phrase search results. Wordtracker is also looking at a precise match and the Overture search engine a broad match. A summary of which keyword analyzer & keyword generator tools to use is at:A keyword generator & analyzer - Which ones to use Keyword analyzer conclusions As with most tools, the quality of the result depends on the tool plus the skill of the user. What I have tried to do through these findings is try to provide some answers as to why these keyword analyzer tools provide such widely differing results.It would be nice to say the correction figures I arrived at on two & three keyword phrase query results could be universally applied. Unfortunately I can't, they are rough guides, a bit like rule of thumb, it applies sometimes, but not all the time. A lot still depends on the skill & experience of the user, but isn't this true of most things in life. Further details about these keyword analyzer tools can be found at: Adword Analyzer Wordtracker Niche Finder | 
