Statistical processing

Source data

The Producer Price Index for Construction of Dwellings is calculated on the basis of prices, reported by selected companies engaged in construction of one-family houses. The sample is selected using a top-down approach by turnover. The collected prices cover 30 to 40 pct. of completed free standing one-family houses i Denmark every quarter. Furthermore, the price information is enriched with information from the Danish Buildings and Dwellings Register. Currently, only data on free standing one-family houses are collected. This is due to the fact, that construction of one-family houses typically are carried out by just one entrepreneur with one final sales price. Construction of multi-storey buildings typically requires several entrepreneurs that may not have a final sales price for the whole building, which complicates the data collection process.

Frequency of data collection

Quarterly.

Data collection

The prices are collected though an electronic reporting form, which is sent to the relevant contact within the selected companies. All further information is gathered from the Danish Buildings and Dwellings Register.

Data validation

The first validation of the price data happens when prices arrive to Statistics Denmark. Here they are first tested for unusual observations and missing address information. The data is then merged with information from the Danish Buildings and Dwellings Register (BBR). Unmatched data is further examined manually for errors, and the missing information is attempted to be acquired from BBR. If necessary, reporting companies are asked to correct erroneous information. Also, prices in relation to size of dwellings are checked. The process of matching the reported data against BBR-data makes it relatively easy to detect errors, and thus include only relevant dwellings.

Data compilation

The Producer Price Index for Construction of Dwellings is compiled on the basis of prices for type houses as reported by entrepreneurs and information from the Danish Buildings and Dwellings Register (BBR). Every quarter prices of newly constructed free standing one-family houses, which were completed in the relevant quarter, are collected from a sample of selected type house companies. Prices are complemented by address information, which is used to add additional information on the building from BBR. Data that cannot be matched with BBR are manually checked for spelling errors, or by contact to the reporting company. Buildings with a different classification than a free standing one-family house are removed. The final data set is treated to hedonic regression, in order to calculate the price development in the relevant quarter compared to previous quarters. In hedonic regression the modelled price is a function of different characteristics of the house, such as area size, geography, number of rooms, number of bath rooms, roofing materials etc.

Adjustment

Besides data validation and data processing, no adjustments or corrections are made to the data.