The Laspeyres bias in the Spanish consumer price index
Authors: Ruiz-Castillo, J.; Ley, E.; Izquierdo, M.
Source: Applied Economics, Volume 34, Number 18, 20 December 2002 , pp. 2267-2276(10)
Abstract:The CPI compares the cost of acquiring a reference quantity vector at current and base prices. Such reference vector is the vector of mean quantities actually bought by a reference population, whose consumption patterns are investigated during a period prior to the index base period 0. This paper shows that unless the price change between these two dates is taken into account, the CPI ceases to be a proper statistical price index of the Laspeyres type. Among several negative consequences, the most important is that this omission produces a bias in the measurement of inflation: the 'Laspeyres bias'. Using Spanish data, the size of the Laspeyres bias is estimated at -0.061% per year, during 1992-1998. The Laspeyres bias in shorter time periods reached -0.122% per year in 1992, and -0.108 in 1997.
Document Type: Research Article
Publication date: December 20, 2002