adsense page impression

it is completely different from my urchin program

[guoqi]

We used urchin for web log analysis. On the report, we can see that our page view is about 50,000 per day. We run google adsense on almost every page, on adsense report, we only see a page impression of 10,000 -15,000.

Can this be right? Why page impression on Adsense is so much different from real page impression?

[enricotal]

possible reasons:

1) Have you excluded any other bot (like yahoo, msn)?
2) Since ads are slower to load, people might change page before the ad actually loads
3) Not all the ads are paid for, and Free ads do not count on adsense

we currenty have a 1 over 4 actual pages views ratio