Data screening tools in competition investigations are empirical methods that use datasets to evaluate markets and firms’ behaviour in them, identify patterns and draw conclusions based on specific tested parameters. This paper focuses on screens aimed at detecting cartels, as these are by far the most prevalent. It was prepared for discussions on “Data Screening Tools for Competition Investigations” held at the November 2022 session of the OECD Competition Committee’s Working Party No. 3 on Co-operation and Enforcement.