Okay, not all 3 column blogs are killing CPM rates but the design contributes to the problem by making it easy for bloggers to produce ad clutter.
Ad clutter is a big problem
A recent BurstMedia survey revealed that 75% of users pay less attention to ads on cluttered sites.
Additionally, although respondents accept that advertising will appear on a web page, for a majority (52.6%), there is low tolerance for more than two advertising units per web page. More than one-quarter (29.9%) of survey respondents immediately leave a site if they perceive it to be cluttered.
So, it's clear that CTR on these ads will go down as will user engagement on cluttered sites. But why not go for the trifecta! Ad clutter also tarnishes an advertiser's brand equity.
The study also found that, from a content perspective, more niche websites - which attract smaller audiences - tend to have higher clutter.
Niche websites. Hummm. That seems like a nice way to point the finger at blogs without outright saying it.
Advertising CPM rates are dropping
CPM rates have been falling. The Rubicon Project reported an 11% decline in CPM rates in Q3 2008. Federated Media slashed rates on some of their hottest properties. These aren't your run of the mill blogs but sites like TechCrunch and Silicon Alley Insider.
I believe ad clutter is a factor in this decline since it leads to banner blindness, which likely carries over, to some degree, from cluttered sites to those less cluttered. If you think of the Internet as a vast interdependent ecosystem it makes sense that the effects from one part of the ecosystem spill over to all.
The movie Jaws certainly spawned a fear of water beyond just that of the fictional Amity or the New England coast.
Are 3 column blogs really to blame?
Yes! Sure they're not the only reason, but they are enablers to ad clutter. The two sidebar columns are ready made for advertising not to mention inline units in the main content column. A "more is better" philosophy for advertising exists among many bloggers. And on the face, more opportunities to click often do lead to more clicks. But there is a point of diminishing return which then results in lower CPM rates.
Unfortunately this might create a sort of death spiral. As the effectiveness of these ads go down, the CPM rates go down, which encourages bloggers to place additional advertising units on their sites to help maintain their revenue stream. That, of course, pushes CPM rates down even further.
You can be the proverbial shark or the police chief. Bruce or Brody. So pick your blog template wisely.