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Methodological improvement to the seasonal adjustment of the Motor Vehicles Production Index
MVPI seasonal adjustment will be done by directly adjusting the total and the home series and deriving the export series as a residual.
Following a re-analysis of the seasonal adjustment method for the Motor Vehicle Production Index (MVPI), an improvement to the methodology has been introduced from June onwards. The new method means that the seasonally adjusted series of production (of cars and commercial vehicles) for export is derived from the seasonally adjusted series for total production and the seasonally adjusted series of production for the home market. This replaces the method where the series are seasonally adjusted independently.
The change improves the quality of the seasonal adjustment by reducing the revisions to the series that arise when new data points become available. The new method also ensures that the growth rates for total production, production for export and production for the home market are consistent.
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