[Y_Y]

I'd be satisfied with a "beyond a reasonable doubt"-type argument. Somebody pre-registers some hypotheses, like "I've never thought about beanie babies in my life, but I'm going to talk about them in front of my phone. I expect I'll start seeing ads for them at a noticably higher rate then before.". Such an experiment wouldn't be difficult to conduct, but I've never heard of it being done methodically, only noticed after the fact.

I'd be very pleased to see it done though. Complications will certainly arise, so N should be large, and there should be several independent replications.

Maybe it's overly cynical, but this also makes me think of the Volkswagen emissions kerfuffle. Would it be so surprising if the ad software was sophisticated enough to know when it was being tested, and try to play dumb?

[brightball]

My wife and I did this. We don’t watch pro baseball at all and we live in the southeast. Had a 10 minute conversation about the Cincinnati Reds and within a few minutes we were seeing MLB ads on Facebook.

I don’t know how they are doing it…but it happens.