> No one is willing to run the experiments necessary.
Not without reason. Even without the conflict of interest that Nextgrid points out in a sibling post, there's still a significant financial barrier to attempting to measure this stuff. According to a former professor of mine who spent a large chunk of his career studying this stuff, the size of study you need to conduct in order to get any kind of statistical power at all on an ROI study is just absurd. See, for example, the treatment starting on page 15 of: http://www.davidreiley.com/papers/OnlineAdsOfflineSales.pdf
Not without reason. Even without the conflict of interest that Nextgrid points out in a sibling post, there's still a significant financial barrier to attempting to measure this stuff. According to a former professor of mine who spent a large chunk of his career studying this stuff, the size of study you need to conduct in order to get any kind of statistical power at all on an ROI study is just absurd. See, for example, the treatment starting on page 15 of: http://www.davidreiley.com/papers/OnlineAdsOfflineSales.pdf