Hm. How about simply buying ad space at a few local newspaper sites? Sure, it's noisy as hell, but maybe still a decent proxy variable. Plus, maybe it's possib

Hm. How about simply buying ad space at a few local newspaper sites? Sure, it's noisy as hell, but maybe still a decent proxy variable. Plus, maybe it's possible to somehow offer a coupon for those who buy via the ad, and so on. After all the ad/tracking industry probably have a thousand tricks to increase accuracy of this. But, yeah, I'm not holding my breath for a conclusive answer on this.