Display Advertising Impact : Search Lift and Social Influence

We study the impact of display advertising on user search behavior using a field experiment. In such an experiment, the treatment group users are exposed to some display advertising campaign, while the control group users are not. During the campaign and the post-campaign period we monitor the user search queries and we label them as relevant or irrelevant to the campaign using techniques that leverage the bipartite query-URL click graph. Our results indicate that users who are exposed to the advertising campaign submit 5% to 25% more queries that are relevant to it compared to the unexposed users. Using the social graph of the experiment users, we also explore how users are affected by their friends who are exposed to ads. Our results indicate that a user with exposed friends is more likely to submit queries relevant to the campaign, as compared to a user without exposed friends. The result is surprising given that the display advertising campaign that we study does not include any incentive for social action, e.g., discount for recommending friends