Discrepancy between Adsense impressions and webstats

do we know that clicks aren't also up the creek?

[John_Caius]

I know this impressions discrepancy has been looked at before, but I'm not sure whether we've ever questioned the clicks accuracy. My site has virtually no PSAs showing and Adsense on virtually every page, with pretty accurate ad targeting. My own logging of traffic shows far more page views than the reported Adsense impressions. If the Adsense page impressions count is out by a factor of 2 or more, do we know whether the Adsense click count isn't also out by the same factor?

If I believe Adsense figures then I've got a nice healthy CTR that matches the normal single-figure kind of numbers you might expect for usual ad click-through rates. If I believe my own figures then I might be some way below that.

[linear]

In my own case, I reckon they're quite accurate.

Once I account for
- bot visits,
- things my stat analyzer thinks are pages but aren't
- alternate ads (you can't coun't PSAs-- you won't know if you're serving "virtually no PSAs" unless you have an alternate defined),
- pages without adsense,
the numbers tote up quite nicely, and hte deiscrepancy due to non-JS browsers is likely to account for the difference, but I see no return on the effort required to account for it at that level.

Another forum member uses a javascript for tracking, this would be the ultimate way to go because it neatly cancels around all the user agent issues. Try that for a week and see if you don't think the numbers agree.

[jomaxx]

I believe the problem is not with the accuracy of Google impression reporting, it's that people try to extrapolate pageviews from their own logs into AdSense impressions by making assumptions that have varying degrees of accuracy. Since you can't track AdSense clicks from your own site, it would be very hard to have any basis for questioning the click numbers.

Overall, tracking impressions and clickthroughs is such a straightforward task that I have no doubt Google's numbers are accurate. I would even call it trivial, except that they must have to combine stats from multiple servers.

[John_Caius]

Ah, maybe it's that I'm counting bot impressions in my own stats. Thanks for the insight. :)

[Jenstar]

Also keep in mind if your server keeps track of stats in a different time zone than Google, which is Pacific Time Zone (PST) - they will kind of balance out over a week/month, but if your server is on AdSense time, it will be easier ;)