A study, conducted in the first quarter of 2007, found that US consumers were more likely to make a purchase after viewing ads on multiple Web sites, suggesting that conversions should be attributed to a full set of impressions and/or clicks, rather than just the single one that preceded the conversion.
Two out of three consumers who eventually bought a product or took a responsive action were reached by ads across multiple portal sites before converting.
Nine in 10 consumers who converted were reached by placements other than the last ad seen. Also, 86.1% of ads which led to a responsive action were seen on multiple placements.
A previous Atlas study called "The Combined Impact of Search and Display Advertising" showed that sponsored search and display advertising together provided a 22% higher conversion rate over search alone.
Of course, multiple placements are not right for every campaign, and they are not always easy to make. A June 2006 study by WebAdvantage.net
found that 79% of experienced online video ad buyers were very or somewhat concerned about sizing ads for multiple placements.