What on Earth has given so many people in this thread the confidence to assert that marketing departments actually have any real way to gauge the effectiveness of a given ad campaign? It's effectively impossible to adjust for all the confounding variables in such a chaotic system, so ad spend is instead determined by internal politicking, pseudoscientific voodoo, and the deftness of the marketing department's ability to kiss executive ass. This ain't science, it's perversely-incentivized emotion.