Determining Ad ROI, Attribution Is Nearly Impossible

Yes, you always knew it and now there's proof - from Google and Microsoft no less.

The paper is called "On the Near Impossibility of Measuring the Returns to Advertising" and is about a year and a half old.

For those of you who do not have the time (I'm looking at you — all of you!) here's the TL;DR version:

Using 25 online field experiments, representing $2.8 million in ad spend, Randall A. Lewis (economic research scientist, Google) and Justin M. Rao (economic researcher, Microsoft) showed that you cannot measure the causal impact of choice variables on profit even given access to reliable signals. Read more...

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