From a branding perspective, click through rates are a poor metric, because one needn’t click a banner to be impacted by it.
According to The Wall Street Journal, ad-technology and Web-measurement companies (namely Microsoft) are trying to engineer a comeback for display ads, offering data that they say show display advertising is more effective than marketers think.
The debate revolves around what leads consumers to take actions on the Web: buying something, printing a coupon or visiting a Web site. Up to now, most advertisers judged the effectiveness of an ad campaign by what consumers did after they clicked on the ad. But some marketers say they are now using research not only from Microsoft, but also independent Web-measurement firms like comScore and Omniture, to figure out what happens before people click on ads — even in situations where they don’t end up actually clicking on the ads.
The major conclusion of this research: By the time consumers search for a product or service, they’ve often already made up their minds to buy it. And display ads are often an important factor in their reaching that conclusion.
My conclusion: buy all the search terms you want, but back them up with display ads.