Designing to encourage CPM ads?

Do advertisers prefer certain sizes?

[farmboy]

I might should post this on the AdWords board, but I thought I'd try here and get some input from those who do both AdWords and AdSense.

A couple of weeks ago, a CPM ad took over an entire 300 x 250 on one of my best pages. When I saw how much I was earning off that, I decided at that rate they could have all my ad space. :)

Anyway, can CPM advertisers target any size ad or are there limitations? Is there certain size ads I should consider if I want to try and attract more CPM ads? Do CPM advertisers prefer certain sizes?

FarmBoy

[ken_b]

If you're talking about image ads, I think they can target sizes by simply running only the size ad that they want to use.

Look in your ad review panel and see what size ads are being targeted to your site by each advertiser.

I often see only one size, other times there seems to be a ad version for every possible ad size when I approve or disallow ads.

[ecmedia]

My understanding is that 300 x 250 is the most popular ad format and other preferred formats are 120X600 and 728X90.