Abstract
This paper focuses on the core inflation measurement in Italy using univariate (national-level inflation) vs. multivariate (city-level inflation) models during the period 1970–2006. We derive algebraic expressions that allow comparison between the reduced form parameters of univariate and multivariate local level models in the context of contemporaneous and temporal aggregation. We illustrate the relevance of these theoretical results for the empirical analysis of time series. Using Italian data, we find that multivariate and univariate models extract similar core inflation measures when analyzing the moderate-low inflation period. In contrast, the two competing models yield different trends when modeling the Great Inflation period.
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Notes
Other approaches have been adopted to analyze the dynamics of inflation in Italy. For example, a common trends model applied to a small-scale macroeconometric system including the inflation rate, a measure of economic activity, oil prices, money, and wage growth rates covering the period 1970–2006 was used by Bagliano and Morana (1999) to estimate core inflation in Italy. Recently, Bacchiocchi (2009) investigated the determinants of inflation in Italy since the beginning of the 1970s until the first years after the launch of the European Monetary Union.
We refer to Mills (2009) for a retrospective analysis on the modeling of trends and cycles in time series.
We use the FOI CPI (“Indice dei Prezzi al Consumo per le Famiglie di Operai e Impiegati”): it is a index for industrial and clerical workers households, which was closely watched in Italy, especially before the EU harmonized consumer price index (HICP) was published. The regional capitals are Aosta, Torino, Milano, Trento, Venezia, Trieste, Genova, Bologna, Firenze, Perugia, Ancona, Roma, L’Aquila, Campobasso, Napoli, Bari, Reggio Calabria, Palermo, Cagliari.
Test results are not reported due to space limitations but are available from the authors upon request.
In fact, as first shown by Wei and Stram (1988), when \(m\rightarrow \infty\), both \(\Uptheta_c\) and \(\Uptheta_a\) converge to a limit of 0.268, which corresponds to the eigenvector associated with the largest eigenvalue of the aggregation matrix (i.e., the matrix that maps the autocovariances of the disaggregate model to the autocovariances of the aggregate one).
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Acknowledgments
While assuming the scientific responsibility for any error in the paper, the authors thank the Editor and two anonymous referees for their helpful suggestions. The authors are also grateful to Marco Magnani, Matteo Piazza, Brooke Rutherford, and Fabrizio Venditti for useful comments. The views expressed in this paper are those of the authors and do not necessarily reflect the positions or policies of the Bank of Italy.
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Sbrana, G., Silvestrini, A. Measuring core inflation in Italy comparing aggregate vs. disaggregate price data. Cliometrica 5, 239–258 (2011). https://doi.org/10.1007/s11698-010-0059-7
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DOI: https://doi.org/10.1007/s11698-010-0059-7