Almost as many people respond to online display advertising by searching as do by clicking

"Despite considerable speculation about the relationship between search engine marketing and online display advertising over the years, the findings from this new study indicate that the two channels have a closer relationship than many marketers may have thought. In fact, the study shows that Internet users initially respond to the medium as follows: 31% respond by directly clicking on an ad; 27% respond by searching for the product, brand, or company by launching a search on a search engine; 21% respond by typing the company Web address into their browser and directly navigating to the website; and 9% respond by investigating the product, brand, or company through social media venues. Overall, 52% of Internet users actively respond to online display advertising."
Source: Study conducted by Search Marketing agency iProspect, reported in a press release, 11th May 2009