Macroeconometric Models and Changes in Measurement Concepts: An Overview* Charles G. Renfro Alphametrics Corporation, PO Box 2566, Bala Cynwyd, PA 19004-6566 Tel: 610\664-0386; Fax: 610\664-0271; Email:
[email protected] This paper introduces the latest report of the Seminar on Model Comparisons, being a set of articles that describe subsequent effects on representative US macroeconometric models of the most recent benchmark revisions in the US National Income and Product Accounts. These accounts state the definitional relationships between measured macroeconomic variables. They also provide an evolving view of the characteristics of the US economy, this evolution occuring as the result of occasional changes in the accounting constructs. In some cases, the changes simply reflect the effect of differences in the availability of the underlying primary measurements. However, in other cases, they are made in order to bring the accounting concepts into better conformity with economic concepts, or for the sake of harmonizing the US accounts with those of other countries. In all cases, such changes may nevertheless affect the particular use of these accounts, implying the need for users to make a careful evaluation of the implications. This paper provides a perspective on the most recent of these changes. 1. Introduction The immediate stimulus for this special issue of the Journal of Economic and Social Measurement is the recent mid-decade benchmark revisions in the US National Income and Product Accounts (NIPA), which among other things instituted a change in the way in which implicit price deflators are computed and used [66, 76, 77, 96, 101].