ABSTRACT
Despite considerable effort to standardize the data, coverage, practices, and definitions differ among countries, and the usual warnings about using the figures carefully still apply. Moreover, cross-country and cross-time comparisons always involve complex technical problems that cannot be fully resolved. Although the data are drawn from authoritative sources, readers are urged to take these limitations into account in interpreting the indicators, particularly when making comparisons across countries. These limitations should also be taken into account when comparing country figures with world and OECD figures.
