The importance of obtaining quality I-O tables for the GTAP Data Base has prompted the need for a method to compare contributed I-O tables. Comparisons are useful for a number of reasons. a) Time comparisons can be used to show how an economy has changed over time. b) Country comparisons may be used to show differences in cost or use structures between countries. c) Comparisons may also be used to highlight errors in construction procedures or mappings and therefore assist us in improving the quality of the data. In this document we look out how entropy can be used to compare I-O tables. The paper is intended to be a practical guide to users who wish to view, examine and use the results from the entropy methods used in the GTAP data Base I-O checking procedure. Section 1 outlines the entropy method used to compare IO tables. Section 2 provides a step by step guide to users on how to view and interpret the results of the entropy programs and section 3 looks at some examples of the entropy program results.
