This chapter presents relevant methodological information on the productivity indicators available in this publication and/or disseminated in the OECD Productivity Statistics (database). It discusses the different existing concepts of hours worked and describes the sources used to measure hours worked for the purposes of productivity analysis. It provides a brief description of capital stocks and capital input measures available at the OECD, highlighting the distinction between two key measures of capital: the productive capital stock and the gross (or net) wealth capital stock. The chapter also provides a summary of the major changes introduced by the System of National Accounts 2008 (2008 SNA), with respect to the 1993 SNA. Further, it describes important measurement issues when tracking price changes in the services sector and the potential significance of price measurement for measured productivity growth in services sectors. It presents the concept of Purchasing Power Parities (PPPs), describing the two different approaches for using PPPs in international comparisons of productivity levels: current PPPs and constant PPPs. The chapter ends with a detailed description of the trend estimation method used to compute productivity trends in this publication.