Brand marketers measuring their display ad performance might not want to rely very heavily on click-through.

Most display ad clicks come from a very small group of consumers, according to “Natural Born Clickers,” a report by Starcom USA, Tacoda and comScore.

The heavy clickers surveyed represented just 6% of the online population, but made one-half of all display ad clicks.

Heavy clickers' demographics were also very different from those of most Internet users. On average, heavy clickers were 25 to 44 years old, with annual household incomes under $40,000. They were online four times as much as non-clickers, but were not big spenders.

Unlike non-clickers, heavy clickers were also relatively more likely to visit auctions, gambling and career services sites.

The researchers said that the data suggested no correlation between display ad clicks and brand metrics, and no connection between measured attitude towards a brand and the number of times an ad for that brand was clicked. Starcom recommended that marketers instead measure shifts in brand attitude and the relationship of ads to sales.

“While the click can continue to be a relevant metric for direct response advertising campaigns...click performance is the wrong measure for the effectiveness of brand-building campaigns,” said Erin Hunter, executive vice president at comScore.

AOL also studied heavy clickers during the summer of 2007, with similar results.

"Ninety-nine percent of Web users do not click on ads on a monthly basis," said Dave Morgan, executive vice president of global advertising strategy for AOL at the time. "Of the 1% that do, most only click once a month. Less than two-tenths of 1% click more often. That tiny percentage makes up the vast majority of banner ad clicks."

Mr. Morgan said that the heavy clickers in the AOL study were predominantly older females who looked at sweepstakes far more than any other kind of content.

"These are the same people that tend to open direct mail and love to talk to telemarketers," he said.

It is important for marketers to know if display ads are helping their brands, since that's often why they use display in the first place.

In a McKinsey study released in September 2007, more marketers used display ads for brand building than to achieve any other goal.

Display ads are not fading away any time soon, either. They account for about one-fifth of online ad spending, and are expected to do so through at least 2011, according to eMarketer. Nearly $8.2 billion will be spent on display ads in the US that year, more than double the 2007 level.

The eMarketer Online Ad Targeting report will be published in March 2008. Click here to be notified when it is released.