Search Engines and Data Retention: Implications for Privacy and Antitrust
This paper investigates whether larger quantities of historical data affect a firm's ability to maintain market share in Internet search. We study whether the length of time that search engines retained their server logs affected the apparent accuracy of subsequent searches. Our analysis exploits changes in these policies prompted by the actions of policymakers. We find little empirical evidence that reducing the length of storage of past search engine searches affected the accuracy of search. Our results suggest that the possession of historical data confers less of an advantage in market share than is sometimes supposed. Our results also suggest that limits on data retention may impose fewer costs in instances where overly long data retention leads to privacy concerns such as an individual's ``right to be forgotten."
We thank Christopher Hafer, Anton Grutzmacher, and James Murray of Experian Hitwise. We also thank Katherine Eriksson for excellent research assistance. While this research has not received financial assistance, in the past Lesley Chiou has received financial support for other research from the Net Institute and the National Bureau of Economic Research. Catherine Tucker has received financial support for other research from Google, the National Bureau of Economic Research, the National Science Foundation, the Net Institute, and WPP. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research.