But does size really matter? In an attempt to answer that question, Web measurement firm Compete recently conducted a study that compared Kohl's ads of different standard sizes that ran April 24 on the home pages of MSN and AOL. MSN ran the familiar 250 x 300 medium rectangle, and AOL ran a 300 x 600 half-page skyscraper.
Both ran on the right side of the page and featured the same creative showing a reduced-price blender and storewide touting of savings and free shipping. As might be expected, the more attention-grabbing skyscraper ad drew 30% more click-throughs per session (1.5% vs. 1.2%).
But the smaller unit was more effective in driving people toward sales -- with 8.3% of those who clicked through to Kohls.com filling up a shopping cart, compared to 6.6% for the larger ad -- a 26% better conversion rate. Consumers who clicked on the smaller ad also averaged more time on the landing page (8.9 minutes versus 7.5 minutes).
"In other words, the larger ad drew the attention of more would-be shoppers, but the smaller ad found a greater concentration of motivated buyers," wrote Compete analyst Alex Patriquin in a post on the company's blog.
Women and consumers with higher incomes were more responsive to both ad units, and each led to people doing same-day online searches for "Kohl's" at the same rate. Compared to a control group of people who had not seen the ads, however, the smaller unit actually delivered higher lift in search activity for the brand.
The humble rectangle got a boost from a separate, more extensive study last month by social media ad company Lotame that focused on engagement. It found that 300 x 250 ads averaged 13 seconds of "viewing" exposure per user served, compared to only 5.4 seconds for leaderboards and 1.9 seconds for skyscrapers.
Compete's takeaway from its ad test was that marketers should look beyond a single metric such as a conversion to grasp the full effect of ad campaigns, and that ads with lower conversion rates can still help build brand awareness.
But this looks more like another upset victory for the rank-and-file rectangle, delivering a better conversion rate and holding its own in brand lift metrics. Maybe it's time for publishers to start thinking inside the box again.