Productivity Research Notes (PRN) is a series of concise analytical briefs produced by the Keio Economic Observatory (KEO), Keio University, Tokyo, focusing on productivity and economic performance in Asia. It highlights key measurement issues, empirical findings, and policy-relevant insights, and serves as a platform to communicate selected results from the APO Productivity Databook/Database and related research activities, including APDB, AQALI, and ANRD.