December 9th, 2011 | Published in Google Research
Advertisers want to be able to measure the effectiveness of their advertising. Many methods have been used to address this need, but the most rigorous and trusted of these are randomized experiments, which involve randomly assigning experimental units to control and test conditions. At Google, we have found that randomized geo experiments are a powerful approach to measuring the effectiveness of advertising.
Many advertising platforms allow advertising to be targeted by geographical region. In these experiments, we first assign geographic regions to test or control conditions and employ AdWords’ geo-targeted advertising capabilities to increase or decrease the regional advertising spend accordingly. The use of randomized assignments guards against potential hidden test/control biases that could impact the measurements. Our approach also accounts for seasonal changes that impact the volume and cost of advertising across the length of the experiment.
In this paper, we describe the application of geo experiments for measuring the impact of advertising on consumer behavior (e.g. clicks, conversions, downloads, etc.). This description includes the results of a geo experiment that our research team ran for a Google advertiser.