Google misreporting page impressions

[Scooter24]

I've placed Adsense blocks on about 30 pages. There is a weirdness in the way Google reports the number of hits. If I choose the aggregate view (all pages) I get a number of page impressions which sometimes is lower than if I choose a subset of the pages. For example:

Aggregate view (all 30 pages, number of page impressions):
April 10: 1587
April 11: 1750
April 12: 1934

Subset view (7 pages out of these 30):
April 10: 2005
April 11: 2166
April 12: 2436

How can a subset of the pages have more page impressions than the total? I'm starting to wonder if they misreport also the clicks.

[spaceylacie]

One is page impressions and one is ad unit impressions, you must have more than one ad unit on some pages.

[Scooter24]

I see - so the aggregate view shows page impressions while the channel view shows ad block impressions.

[trader]

It depends on which 'show data' setting is toggled on the reports page, either page impressions or ad unit impressions. I was also quite confused on this new feature.

i.e. with page impressions set, if you have 10 pages with 3 ad units (blocks) plus 1 adlink on the pages it is reported as 10 impressions and say a CTR of perhaps 5% or more for example.

i.e. conversely with ad units set, if you have 10 pages with 3 ad units (blocks) plus 1 adlink on the pages it is reported as 40 impressions and say a CTR of less than 2% being likely, for example.

That is my understanding but it could always be wrong of course. It's somewhat confusing.

[leadegroot]

There's a little question mark on the 'show data by' dropdown that links to an explanation