Missing Impressions?

[garyfinny]

Hey,

I was hoping that you guys could clear up a mystery for me. I've just started using Adsense on my site, and I'm rather worried I might be doing something wrong.

Basically, the Ad impressions I'm getting don't seem to add up. Let's take a case yesterday, I had 160 uniques, with 806 page views, yet only 37 page impressions. There are only 2 pages on my site which do not have Adsense, so it's unlikely that these pages are getting all the hits.

Interestingly, I have a hit counter for a group of my pages which do have Adsense on... yesterday they got 205 hits... so techically, I should have at least 205 impressions, right?

So here are my questions:
- If a search engine spider views a page, does it generate an Adsense impression? (This could be an explanation)
- If a user views more than one Adsense ad in the same session, does it count as just one impression?
- A lot of the delivered ads seem to be very similar to each other, probably due to the content. If a view sees the same ad (but on another page), does it count as just one impression?
- If I view my own ads (for example, when checking a page), does it count as an impression?
- If I have two Adsense units on one page, does it count for one or two impressions?

Thanks for any help you can give me regarding this matter.

[despot]

Google uses JavaScript to display ads. JavaScript does not get parsed by search engine robots, console web browsers and some older graphic browsers. Also, it can be turned off in browser's settings.
If javascript does not get parsed, the user does not let google know he visits the site and it does not count as an impression.