DoubleClick for Advertisers announced a significant change to their algorithm that will improve how they derive the unique visitors (users) metric in Ad Planner.
The unique visitors (users) metric is the estimated, unduplicated number of people who visit a site over a specific month. This measurement is key to understanding what percentage of your target audience you can reach at any given site.
"We are rolling out our improved algorithm across all of the sites in Ad Planner today, April 19, 2011, and as a result we expect that you will start seeing an increase in the number of unique visitors for most sites. We have spent the past year on intensive research to build this new model and are very excited to finally put it into effect," noted DoubleClick.
Note that the methodology for all other metrics in Ad Planner remains the same with this change.
For more information on how we compile the data in Ad Planner reference this article in the Ad Planner Help Center.
[Source: DoubleClick for Advertisers blog]