shorebreak - 3:48 pm on Jan 31, 2008 (gmt 0)

My former employer - Efficient Frontier - put out a study yesterday comparing Q4 '07 to Q4 '06 across the 3 major SE's and looked at both spend growth (29% Y/Y) and ROI growth (13% Y/Y). That's across ~$500M in annual spend and I take it to mean that spend is growing far, far faster than ROI at this point.

You can find the study on EF's blog.