The producer- and import price index for commodities is based on approx. 6500 prices, reported by selected producers and importers in Denmark. Approx. 3500 prices are used for calculating the producer price index, approx. 2900 prices are used for calculating the import price index and approx. 4900 prices are used for calculating the price index for domestic supply. The prices are collected every month through an electronic questionnaire and validated.
The validated data are then aggregated in a hierarchical system to calculate the producer- and import price indices for commodities.
The Producer- and import price index for commodities is calculated on the basis of about 6500 prices, reported by selected producers and importers in Denmark. Of these, about 3500 prices are used for calculating the producer price index, about 2900 prices are used for calculating the import price index and about 4900 prices are used for calculating the price index for domestic supply.
The weights are based on national accounts estimates of Danish companies' turnover values.
Prices are collected through an electronic reporting form, which is sent out to selected companies.
The first validation of price data happens when prices arrive to Statistics Denmark. Here they are auto tested for unusual developments. The prices that do not pass a predetermined threshold value will be checked manually by the staff and accepted only if the firms can verify the change. When all prices are received, the system generates a list that includes all price changes and a measure of how these affects the elementary aggregates. The last validation is a visual inspection of all index tables.
The Producer and import price indices are calculated in a hierarchical system where the first calculation is made for the most detailed group of commodities, i.e. the elementary aggregates. These indices are calculated as geometric Jevons indices. The detailed elementary aggregates are subsequently weighted together for sub-indices and in the end for the total producer and import price indices. These are calculated as arithmetic Laspeyres indices.
Weights: Weights are assigned to every detailed group of commodities and used for weighting the base indices together for sub-indicies and for the total Price index for domestic supply. The weights, which are based on the supply and use tables from national accounts for 2016, are equal to the sum of the import values and production values for the home market excluding VAT and excise duties. This ensures that the sample reflects the population.
Estimates for non-response: Non-response is negligible. If it should happen for any significant goods, imputation techniques are used. In other cases the prices are regarded as unchanged.
There are no corrections of data beyond what has already been described during data validation and data processing.