Good data-driven marketing teams work hard to establish control groups and known baselines before starting high-spend campaigns, and the ROI of those can be qua

Good data-driven marketing teams work hard to establish control groups and known baselines before starting high-spend campaigns, and the ROI of those can be quantified by referrer info if they're highly specific and keyword-related. As for more general campaigns, in my experience, it's a crapshoot, if the numbers go up everyone is happy whether or not marketing was responsible for the majority of it. I'm sure other companies have better approaches than that though.