The study is based on a statistical model built to predict the change in click rates for given levels of ad spends.The number of organic impressions and spend impressions served as the parameters giving an estimate for the incremental clicks attributable to search ads (IAC) i.e. the percentage of paid clicks that are not accounted for by organic clicks when the paid ad campaigns is paused.

The study was based on 446 campaigns running in Germany, France, Great Britain and the United States from October 2010 through March 2011. The research team examined campaigns that had been paused after running ads for some period of time and then estimated the incremental impact of paid search ads on total search volume.

And the results

The findings of this study found that ad click percentage was as high as 89%, meaning that for a given keyword, a paid ad campaign would generate an 89% increase in traffic to the site over that generated by organic listing. It could be suggested that the data is skewed somewhat because more that half of the campaigns studied were US based with data coming in from the holiday period.

While this study surely answers some important questions frequently asked by advertisers, should they take it as a thumb rule for other search engines as well?