The Online Display Ad Effectiveness Funnel & Carryover: Lessons from 432 Field Experiments

Abstract

We analyze 432 online display ad field experiments on the Google Display Network. The experiments feature 431 advertisers from varied industries, which on average include 4 million users. Causal estimates from 2.2 billion observations help overcome the medium's measurement challenges to inform how and how much these ads work. We find that the campaigns increase site visits (p<10^-212) and conversions (p<10^-39) with median lifts of 17% and 8% respectively. We examine whether the in-campaign lift carries forward after the campaign or instead only causes users to take an action earlier than they otherwise would have. We find that most campaigns have a modest, positive carryover four weeks after the campaign ended with a further 6% lift in visitors and 16% lift in visits on average, relative to the in-campaign lift. We then relate the baseline attrition as consumers move down the purchase process—the marketing funnel—to the incremental effect of ads on the consumer purchase process—the 'ad effectiveness funnel.' We find that incremental site visitors are less likely to convert than baseline visitors: a 10% lift in site visitors translates into a 5-7% lift in converters.

Keywords: advertising effectiveness, field experiments, digital advertising, meta-study

JEL Classification: M37, C93