The study, which was based on 2,390 online display campaigns running over the past three years, found that so-called "half banners" (those measuring 234 x 60) and rectangles (180 x 150) were more effective than ads that frame the page such as high profile leaderboards and skyscrapers.
The Dynamic Logic researchers said the reason is that the smaller format display ads are far more integrated into the content of Web pages, and consequently are more effective at "driving online ad awareness and purchase intent."
Ken Mallon, senior vice president-custom solutions at Dynamic Logic added the caveat that the relative creative quality of each ad is the single most important factor, but that all things being equal, format size can be a significant determinant in campaign effectiveness.
"We continue to believe that creative quality is the most important factor driving the success of online advertising," he stated, adding. "However, it will be interesting to see how the new, larger ad formats that publishers are beginning to debut will rank next to the more traditional online ad formats. Based on the current data, bigger doesn't always mean better, but these new ad formats are quite unique and we look forward to testing them."
Not surprisingly, the researcher also found campaigns using rich media with video created the strongest brand impact compared with campaigns using simple flash and rich media without video formats. The worst performer was simple flash, the format used most often by agencies and advertisers.