The study found that consumers are more likely to convert after viewing ads on multiple Web sites. Consumers reached across multiple publishers were twice as likely to convert than those reached on a single publisher.

Ninety percent of consumers that converted were reached by placements besides the last ad seen. Two out of three consumers who took a responsive action were reached by ads on multiple portal sites before converting.

"The study validates the fact that most marketers need to plan beyond the last ad seen," commented the study’s author, Jed Fowler, Analyst, Atlas Institute. "It’s critical that marketers review all consumer touch-points to determine credit for conversions."

The study reveals that overlapped ads are usually responsible for the majority of online conversions.

"Overlap across publishers has tremendous implications for an ad campaign’s performance, marketers can no longer ignore the magnitude of reaching consumers across multiple sites," concluded Fowler.

The Atlas Institute conducted the study in the first quarter of 2007. The study examined media campaigns of 16 advertisers that ran the gamut of retail, manufacturing and health sectors. The study was based on five billion ads, 1.7 million online sales transactions, leads, registration conversions and over 300 million anonymous users.