UNCTAD provides the most comprehensive dataset on FDI stocks that is currently available in terms of both
its coverage across countries and time. As such, it is the best data source for describing global trends in FDI.
As data on FDI was not available from national sources for all countries and years, UNCTAD imputed some
values in order to be able to make globally representative estimates. In other instances, UNCTAD made certain
statistical adjustments to the data that were provided from national sources in order to enhance their
international comparability. For both these reasons, FDI estimates based on UNCTAD may be different from
those based on FDI data provided by either the OECD or the IMF (cf. OECD FDI Statistics and IMF Balance
of Payment Statistics). See OECD (2008b) for a detailed discussion of international methodological standards
for the measurement of foreign direct investment.