Google Data Collection research (PDF) - by Professor Douglas C. Schmidt, Professor of Computer Science at Vanderbilt University, and his team. This study provides a unique and comprehensive view of Google’s data collection approaches and delves deeper into specific types of information it collects from users.

To understand what data Google collects, this study draws on four key sources:
a. Google’s My Activity and Takeout tools, which describe information collected during the use of Google’s
user-facing products;
b. Data intercepted as it issent to Google server domains while Google or 3rd-party products are used;
c. Google’s privacy policies (both general and product-specific); andd.Other 3rd-party researchthat has examined Google’s data collection efforts.