"Everyone wants the Tiffany box, but there is no Tiffany box," when it comes to Web analytics, said Dave Coffey, director of media services at Sapient, which surveyed 120 professionals directly or indirectly responsible for managing digital marketing budgets. "The lack of customization within analytics tool sets is affecting marketers' abilities to measure what they want and what's important to them."

Online social media presents the biggest challenge, with 35% saying it's the category they're least confident about tracking in real-time. That's also why social networking is expected to see the biggest gain in Web analytics spending in the next 18 months. Forty-two percent of managers plan to use social networking analytics tools in the next year and a half, compared to 12% currently.

What makes social networking especially difficult to measure is its amalgam of different media and communication features including blogging, messaging, video, Web pages and widgets. "One of the main things people find hard is that there's no consolidated dashboard of all this activity," Coffey said. Advertisers may rely on several vendors to track different types of usage within social networks but not centralize the data in one place, he said.

The more established marketing vehicles of e-mail and search were found to be the most trackable online categories, at 32% and 30%, respectively. Search was also the cited as the channel providing the greatest return on-investment to managers' organizations (38%).

And despite the buzz surrounding categories like social networking and mobile, search was where marketers expected to increase spending the most in the next six to 12 months (28%). By contrast, e-mail was the segment marketers planned to cut spending on the most in the next year. That suggests measurability isn't always the most important factor in determining digital marketing spend.

The biggest proportion of those surveyed (25%) said they based spending allocation on demonstrable success in prior campaigns, followed by the ability to track digital tactics to revenue (20%), advice provided by my agency or colleagues (18%) and information provided by analytics tools (17%).

More broadly, the study showed advertisers are concerned about the impact of mergers shaking up the industry in the last year. That M&A wave included Microsoft's acquisition of aQuantive and Google's purchase of DoubleClick. Forty-one percent fear getting lost in the shuffle with thousands of other clients because of consolidation in the online advertising business.

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