Using Engel curves to measure CPI bias for Indonesia

Abstract

To measure real income growth over time, a price index is needed to adjust for changes in the cost of living. The consumer price index (CPI) is often used for this task; but several country studies show that it is a biased measure of such changes, leading to potentially inaccurate estimates of the rate of real income growth. This paper calculates CPI bias for urban Indonesia by estimating food Engel curves for households with the same level of CPI-deflated incomes at four different points in time between 1993 and 2008. The results suggest that CPI bias was negative during the 1997–98 crisis but has been positive since 2000. From 1993 to 2008, CPI bias averaged 4% annually, equivalent to almost one-third of the measured inflation rate.