I am seeing a trend where my percentage of text ads impressions is going way down and want to know what might be causing this.
The first ad on my pages in a 728x90 in a very visible location. Until recently, I would run all ad formats and text would be 75% of the impressions. In the last couple of weeks, now text is only about 10-15% of the impressions. The text ads work the far and way the best. So the first thing I did was set the ad to text only. Well doing that reduced the CPC and RPM substantially. I'm just trying to figure out what changed that shifted most of the ads to rich media/image and away from text. There are plenty of advertisers running text ads in this size so inventory isn't the problem. I guess the only thing I can conclude is that Google's system has a bug or that Google just wants me to run rich media/image ads because they think I/they will make more money. But the data shows they don't make more money forcing all these rich media/image impressions on me.
I ran text only on 1 page for a week. These are high volume pages, 200K pageviews a day. When I run the text only, CTR and RPM decreases by about 50%. And when I turn back rich media/image ads back on, the overall CTR and CPM jumps back up. But like yesterday, text was far and away the best performing ad type when all ad types are back on.
I just don't get why Google's system changed to show a low percentage of text ads now when I am opted in all ad types.