ClickZ and MediaPost offer different takes on behavioral-targeting research issued today by 24/7 Real Media, the former emphasizing the increase in click-through rates for ads using behavioral targeting, and the latter pointing out that such results were inconsistent. Click-through rates can climb by as much as 250 percent, according to 24/7's second Quarterly Targeting Research Report, which cites the example of a major movie studio that used behavioral targeting to increase average click-through rates on movie ads by 25 percent compared with ads targeted demographically.

Overall, the report concluded, advertisers saw higher click-through rates, but not consistently. "There are no hard and fast rules that we could draw," according to a 24/7 spokesman. "It depends on who you're targeting and how well you know that audience."

The report also says that behavioral targeting increased the value of participating publishers' lower-tiered ad inventory up to 550 percent. On average, the report concluded, publishers increased the value of their inventory by 22 percent by using behavioral targeting.

One example of an initiative that didn't work involved a fourth-quarter effort to serve ads to web users categorized as potential DSL subscribers based on visits to tech sites. The results would have been betterhad the ads been limited to those connecting via dial-up, according to the report.

The use of behaviorally targeted advertising is expected to increase 65 percent and account for nearly 21 percent of all online ad buys in 2006, according to a recent study.