https://productforums.google.com/forum/#!topic/adsense/2frvdOVxz2g
https://support.google.com/adsense/answer/55613?hl=en
Neither arguments were entirely satisfying to me. I for example was seeing, in the Blogger Stats for my Ocean Videos site, more than 30 hits PER DAY, whereas Google Adsense only saw 28/WEEK. I was even more puzzled, based on studying the difference in page hits between various posts. I had been sending out tweets for each new posting, and tweets that I knew were more-well-written and/or to more-interesting pages were getting a 3-5X higher number of hits. This seemed to be proof that Adsense was messed up. (I didn't think Google was scamming us but that perhaps there were some laziness or lack of clarity about the policy for "activating" ads).
I noticed that the minimum number of hits was 3 for a tweet. So I tested the "tweet interestingness" theory by using a junk, alternative Twitter account with only 32 followers. I put in four nonsense-letters, followed by a link. It got at least 3 hits. This made me wonder if there were THREE bots scanning twitter, and hitting on every URL posted.
So I did some math. I took the top ten page hits according to the Blogger stats, and subtracted three from every page. The total was 25. Google Adsense's performance report over the same period said I had 28 impressions.
Mystery solved. There are three bots harvesting (my) Twitter-posted URL's. Adsense ignores the bots.
