Campaign with geolocation restrictions exceeding daily limit

[Thomas Schenkeli]

Hi,

we do have certain campaigns that constantly exceed their daily limit and we do not understand why.

Our original problem was that we had CPM campaigns with a e.g. 125.000 impressions to be shown over a course of three months and a rather strict geo-restriction (a single federal state in Austria). So we would expect something around 125.000 AI / 100 days = 1250 impressions per day.

but it looked like this:

1st day: 3.900
2nd day: 15.000
3rd day: 4.200
4th day: 5.200
 

It then went down again on average, but some days it went up to around 9.000 ... and after around a month almost all AIs were delivered with nothing left for the remaining two months.

So we changed the campaign to a daily limit of 400 AI per day. This again worked for a few days:

432
322
423
592

but after these four days the ad server panicked again and deliverd:

5014
2603
3205

The geo-restriction shouldn't be a problem since we have around 1 million of page views per day in Austria, so limiting the campaign to one of ten federal states over three months should provide more than enough inventory (ad actually does since the ad is delivered, just way too often too fast).

This problem only occurs on our ad zone for rectangular content ads (300x250) - we do have identical campaings for our skyscraper / halfpage ad-zone and they work exactly as expected.

The only significant difference I see between the two ad-zones is that for the affected content-ad zone we do have another big campaign that uses roughly 30.000.000 AI of the available 60.000.000 per month - but the remaining 30.000.000 per month should be more than enough to fulfill the 125.000 impressions over three months - even with a geo-restriction.
On the skyscraper ad-zone the majority of the inventory is used by remnant campaigns (e.g. Google Ad Sense).

There are no other campaigns running with the same geo restriction for the same geographical region.

Our intentional over delivery is set to 10% - but that doesn't explain why 10 times the configured amount is delivered.

Any ideas? Any help or input would be appreciated - thanks!

Thomas