Google just posted an update to its Search Ads Pause Studies Update, which was first released in July 2011. The study called "Incremental Clicks Impact of Search Advertising" showed the amount of search ad traffic that is incremental to traffic from an advertiser's organic search results.
Google said that they have found that "an average 89% of paid clicks are essentially lost and not recovered by an increase in organic clicks when a search campaign is paused. This number - what we call the Incremental Ad Clicks (IAC) - was consistent across all verticals."
In this update, Google said they looked at three additional change scenarios and included new cases up to August 2011, giving a total of more than 5,300 cases.
For the paused cases, the "average IAC of 85% was a little lower than the previous value of 89%. We see there was some volatility in this estimate, month-to-month, driven purely by the mix of advertisers who choose to pause their ads in that month," Google informed.
In the cases where spend was decreased (as opposed to paused), Google said they found that the "ads associated with the spend decrease drive on average 80% incremental traffic. This means that 80% of the traffic from those ads wouldn't be made up for by organic traffic. This value is lower than the 85% value in the paused cases, possibly due to advertisers selectively turning down parts of their search advertising which they find less effective."
And, in cases where an advertiser was already spending on search ads and subsequently increased their ad spend, Google found the associated ads drive, on average, 78% incremental traffic. In the last scenario, where advertisers were previously not advertising with search ads, and then turned on search ads, the incremental traffic was 79%, Google added.
Check the infographic below: (click to enalarge)