Errors in Geotargeted Display Advertising: Good News for Local Journalism?

The rise of geotargeted online advertising has disrupted the business model of local journalism, but it remains ambiguous whether online advertising platforms can effectively reach local audiences. To address this ambiguity, we present a focused study auditing the positional accuracy of geotargeted display advertisements on Google. We measure the frequency and severity of geotargeting errors by targeting display ads to random ZIP codes across the United States, collecting self-reported location information from users who click on the advertisement. We find evidence that geotargeting errors are common, but minor in terms of advertising goals. While 41% of respondents lived outside the target ZIP code, only 11% lived outside the target county, and only 2% lived outside the target state. We also present details regarding a high volume of suspicious clicks in our data, which made the cost per sample extremely expensive. The paper concludes by discussing implications for advertisers, the business of local journalism, and future research.