On the persistence of prices in Mexico: a fractional integration approach

A relevant yet often overlooked characteristic of the inflation rate is its mean-reverting property. If a series has this feature, shocks eventually dissipate, whereas if it does not, they have a permanent effect on the series. The usual I(1) versus I(0) dichotomy in time-series econometrics goes only so far towards disentangling this issue. By employing a methodology that estimates the persistence of inflation by allowing (i) fractional integration and (ii) persistence and level shifts in the series, we aim to define whether it is stationary and/or mean reverting and, if so, during which periods. The results of our analysis for the period 1987–2015 are threefold: firstly, inflation in the eighties and nineties should be seen as a highly persistent yet mean-reverting process (not a random walk); secondly, inflation remained mean reverting, though became a short-memory (less persistent) process around the date of the implementation of the inflation-targeting framework of 2001; thirdly, during the later phase, the level of inflation also decreased and is now within the inflation target range set by Banco de México, namely 3 per cent with an interval of ±1 percentage point.