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Consumer Spatial Price Indices - Year 2022
Istat publishes the 2022 update of consumer spatial prices indices at regional level for the expenditure divisions Food and non-alcoholic beverages, Alcoholic beverages and tobacco, Clothing and footwear, of the Ecoicop classification (European Classification of Individual Consumption by Purpose), already published in 2023 for the year 2021. Moreover, new indices cover two further divisions: Furnishing, household equipment and routine household maintenance, and Restaurants and hotels. The process of progressive coverage of the expenditure aggregates continues within the experimental project aimed at providing an estimate of the consumer spatial prices indices at regional level (Sub National Spatial Price Indices or Regional Purchasing Power Parities), i.e. a synthetic measure of the relative price differential existing between one region and another.
Sub National Spatial Price Indices (SN-SPIs), in fact, measure the differences in the price level of a basket of products across regions within a country at a given point of time. They are therefore an important tool to have a more accurate reading of the inequalities and living household conditions across territories, due to the differences in purchasing power.
The SN-SPIs computation needs many detailed data at local level for a group of products that are representative of the consumer behavior in different areas. The basket of products must guarantee the requirements of representativeness and comparability. Representativeness relates to the importance of the product in consumer expenditures within a geographical area. Comparability, on the other hand, is guaranteed by the presence of products with the same or similar characteristics, so that any differences in the price levels are, in no way, attributable to the differences in quality.
The sources used for compiling these new indicators are mainly those of the consumer price survey complemented by surveys carried out for the specific purpose of calculating the regional spatial indices. In summary, the three data sources are:
- Scanner data. A unique identifier (bar code) characterizes each product, therefore the comparability in space is guaranteed. Information on turnover and quantity allows to calculate the unit value (average price) for each bar code and to weigh it, fully guaranteeing the principle of representativeness.
- CPI (Consumer Price Index) data. For some product categories (fresh fish, fruit, and vegetables, cleaning of clothing, domestic services by paid staff and cleaning services, some catering services and accommodation services), the definitions in the traditional CPI data collection are detailed enough to allow the use of these data in compliance with comparability. The products of these categories included in the consumer price basket are widely distributed throughout the country.
- Ad hoc surveys carried out in the regional capitals, with the addition of Padova and Bolzano, excluding L’Aquila for products not covered by scanner data or with too generic definitions, which do not guarantee comparability, in the territorial CPI survey. For these products, ad hoc surveys were the only way to ensure comparability and representativeness. Even if the territorial coverage of these surveys does not reach the detailed level of the other sources, it is sufficient to guarantee reliable estimates. The surveys were conducted by the Municipal Statistical Offices of the municipalities involved, on a basket of products selected by Istat considering their share of household expenditure within Ecoicop division and the information on the importance of the single product provided by the municipal coordinator. The surveys are carried out using the CAPI technique (Computer assisted personal interview).
The methodology used to compute SN-SPIs is that recommended by the International Comparison Program (ICP) and used by the World Bank.