No data, no value?

From Jeremiah Owyang's Web Strategy Summary:
"As scrutiny over marketing budgets will increase, there is more discussion online about the value of marketing and advertising on social networks. Although we continue to see anecdotes and case studies, we’ve yet to see any social network offer a ROI on marketing efforts –or even public data. "

Hmmm... why is it always so difficult to demonstrate value from marketing communications efforts? What are your thoughts? Do your execs demand evidence, or are they confident that the value is there, even if you don't have the numbers to prove it?

Here are David Meerman Scott's views on this subject.