The new national consumer price index (NCPI) on which the health index is based came into effect in January 2014. It underwent full revision, as it does every eight years. This brings to an end the significant obsolescence of the index, in which the weighting scheme increasingly failed to reflect real consumer behaviour, a fact which had implications for the inflation figures. On this occasion, various methodological adjustments were introduced, most of them corresponding to the changes announced previously during 2013. The most important innovation is the switch to the use of a chained index instead of a fixed base. That decision will make it easier not only to implement gradual methodological improvements in future, but above all to adapt the weighting scheme annually and thus regularly reflect observed changes in consumption habits. The set of changes will influence the inflation figures according to the NCPI and the inflation gap between that and the harmonised index of consumer prices (HICP). Although the NCPI methodology has been brought closer to that of the HICP, the two indexes are likely to continue to display divergent movements owing to the remaining methodological differences, particularly between the weighting schemes, though the effect will be smaller than in recent years.
