Position Estimates in Yahoo

I'm becoming much more familiar with the new Yahoo interface, but there's something that's still confusing to me is the Position Estimate in the Bid Screen.

I'm using the Standard Match Type on all of my terms, so there should be very few combinations that will match my terms. I'll do a search for one of my terms on Yahoo and find it on the 7th page. Then I'll go into the Bid Screen for that term and when I look at the Position Estimate, it will say 4.5.

How can the Bid Estimate be 4.5, when my word is on the 7th page? I realize this is probably an estimate of all the possible terms that can match my term, but since I'm using Standard Match Type, there shouldn't be too many.

My concern is this:

When I add terms to my account, I usually do a search for them on Yahoo and try to bid them as close to the first 2 pages as possible without bidding over $3.00, but when I find a word on the 7th page and I bid $3.00 to bring it up to the 2nd page, but the Yahoo Position Estimate is telling me I'll be in the 3rd position, then I start to think I might not really need to bid to $3.00. I don't want to bid too high, but I also don't want to be too low so my ads are never seen.

Thank you for any advice you may be able to offer.

James