A new study from aQuantive’s Atlas Institute has looked at the effects of running ads across multiple publishers, portals and ad networks, and found that this can have a positive effect on conversions.

The study (PDF), (via Google’s CPG Blog) found that users that are reached across many sites tend to be more avid media consumers, and are often responsible for the majority of conversions.

The study looked at 16 advertisers that used Atlas to track their campaigns in the first quarter of the year. It covered 5bn ads served and 1.7m conversions.

It found that users reached by campaigns across multiple publishers represented around a third of the number of users reached, but accounted for two thirds of conversions.

Atlas recommended that overlap is most effective for branding campaigns, as well as noting that the impact of overlap on conversions will vary between advertisers as “there is no consistent correlation between reach and conversion overlap”.

Further reading:

Online Advertising Networks Buyer’s Guide 2007