Advertisers often wonder whether search ads cannibalize their organic traffic. If search ads were paused, would clicks on organic results increase and make up for the loss in paid traffic? Google statisticians recently ran over 400 studies on paused accounts to answer this question.

In what we call "Search Ads Pause Studies," our group of researchers observed organic click volume in the absence of search ads. Then they built a statistical model to predict click volume for given levels of ad spend. This model generates estimates for the incremental clicks attributable to search ads or, in other words, the percentage of paid clicks that are not made up for by organic clicks when search ads are paused.

On average, the incremental ad clicks (IAC) percentage across verticals is 89%. This means that a full 89% of the traffic generated by search ads is not replaced by organic clicks when ads are paused. This number was consistently high across verticals. You can find a video on the study here. The full study can be found on

Posted by Lauren Barbato, Inside AdWords crew

Editor's note (Tuesday, August 9, 2011, 11:17 am): The analysis is based on studies conducted on 446 advertiser accounts between October 2010 and March 2011.