Does advertising measurably affect sales? New technologies for tracking individuals’ sales and ad exposure facilitate studying a nationwide retailer’s online brand advertising effectiveness. A controlled experiment on 1,577,256 existing customers measures the causal effect of advertising on...

A randomized experiment with 1.6 million customers measures positive causal effects of online advertising for a major retailer. The advertising profitably increases purchases by 5%. 93% of the increase occurs in brick-and-mortar stores; 78% of the increase derives from consumers who never click...