"Measuring the Real Size of the World Economy: The Framework,
Methodology, and Results of the International Comparison
Program—ICP is the most comprehensive accounting ever
presented by the International Comparison Program (ICP) of
the theory and methods underlying the estimation of
purchasing power parities (PPPs). PPPs reveal the relative
sizes of economies by converting their gross domestic
products and related measurements into a common currency,
thereby enabling comparisons based on economic and
statistical theory.