Users filtering ads?

Is this something that ad blockers/javascript off can do?

[freitasm]

I've noticed that with AdSense and with LinkExchange (although I'm not using it anymore): the number of impressions is sometimes 60% of the number of my served pages.

Today I had my busiest day since joining AdSense. The stats says 4,801 impressions, while my server says 7,400 pages served.

I take this could be users blocking javascript, either on the browser, or using ad blocking software.

Makes sense?

[Jenstar]

From the Google AdSense FAQ:

3. Why do I detect a different number of impressions than what shows in my reports?
We count impressions only when our ad code is executed by a user's browser. There are therefore several factors that would cause a discrepancy between the impressions you register and the impressions listed in your AdSense account. Instances that wouldn't execute the code include:

Other spiders, robots, crawlers from other search engines
Browsers that don't have JavaScript enabled or don't support JavaScript
Browsers that don't support the <iframe> tag
Programs that people may have written to grab website content

[freitasm]

Thanks. I realise that. I'm more interested to know about experiences other sites have, if this is the same range in terms of %.

[jrstark]

I put my AdSense code in an include. The hits to googlesky and googlehoriz come very close to the number of impressions google is reporting.

I do have a situation right now where the ads are not showing at all in some browsers. Some, but not all, folks using IE 5.5 see the background showing through. No ads whatever, no link either. The AdSense code is there when you view source. This is not the blank space ad, you never know the ad is there. If the layout allows, other text fills the space.

Don't know how widespread this is, only know of two cases so far.

[richmondsteve]

Also keep in mind that Google's timezone for reporting is PST (GMT-8) so if your server's timezone is different and daily page views fluctuate a lot that can have an effect. In my case I believe the reasons from the FAQ Jenstar pointed out explain most of it.