Major discrepancy between Analytics impressions and Adsense impression

Doubtful that it's just related to ad blockers

[dazzlindonna]

A friend of mine mentioned that his Google Analytics page impressions and Adsense impressions were way off. At first I just didn't think much of it, but I checked my numbers for this month just to see if there was anything strange, and indeed there is.

I run two sets of analytics on each page - both Google Analytics and Clicky. Both are close enough to each other to be believable - both are in the 600,000 range for December to date for one site.

Yet, Google Adsense page impressions is approximately 100,000 less.

100K impressions gone missing could be some significant $$ gone missing.

I realize that ad blockers could explain some of it, but I doubt it would explain 1/6 total. Those of you running GA, do you see similar discrepancies?

[IanCP]

I've found Analytics to be so far off AdSense as to be valueless.

From memory, only 30 - 40% of revenue is reported as one example.

[Robino]

I usually see a 15-20% discrepancy. And it could go either way.

Last month, on one of my sites, Adsense reported 18% more pageviews than Analytics did. (and I'm not filtering any traffic)

[dazzlindonna]

I probably should have compared them over the years, but I just haven't. So while it may be "normal" to be so far off, since both analytics programs are reporting similar numbers, and Adsense is reporting so much less, I have to assume it's a problem with Adsense. But I figure there are lots of y'all who have compared the numbers more than I, so looking for feedback. (Knowing this is the best place to get it. Sure won't get any from Google. LOL).