Statistical processing

Source data

To calculate the indices for refuse collection, slurry pump and freight transport by road mainly data (prices) from other statistics in Statistics Denmark are used. Monthly prices of some goods and services are collected from Price index for Domestic Supply (PRIS1115) and the Net Price Index (PRIS116). See the statistical documentation for these indices for more info. Labour costs relate to wage rates fixed by collective agreements between Danish Industry and the United Federation of Danish Workers (previously the Danish Specialized Workers' Union). Fuel prices are gathered as quarterly averages of daily prices from fuel stations incl. various taxes but excl. sales tax.

The weight basis is developed in collaboration with Danish Transport and Logistics and Danish Industry. Index calculations include costs of labour, social costs, repair and maintenance, fuel, tires, administration, insurance and capital costs.

Frequency of data collection

Primarily quarterly. Some prices are gathered monthly or yearly.

Data collection

Some materials prices are collected from Price index for Domestic Supply (PRIS1115) and the Net Price Index (PRIS116). See the statistical documentation for these indices for more information on methods. Furthermore, some prices are collected from the internet, collective agreements and reporting by collaborators.

Data validation

The initial data validation is done when collected prices are loaded in Statistics Denmark's dedicated calculation system, which generates a list of all price developments. An automated test for unusual developments from one period to the next is performed. Price developments that exceed a fixed threshold value are only accepted if such developments can be accounted for by reporting entities. The final validation is a qualitative evaluation of the calculated indices.

Data compilation

The Cost index for refuse collection, slurry pump and freight transport by road is calculated by a hierarchical system, where the collected prices are divided into a number of product groups. These groups are aggregated into basic aggregates, which form basic prices using geometrical averages. Basic indices, which is the most detailed index level, are then calculated as the development between basic prices in two consecutive periods. Using the Laspeyres type index method, the basic indices are weighted to aggregated subindices, which are then weighed to the aggregated total indices - the top level in the index hierarchy.

Basic aggregates include costs of labor, repairs and maintenance, fuel, tires, administration, insurance and capital costs. For the calculation of indices excl. fuel, the fuel category is removed from calculations.

The combined aggregation from basic prices to total indices uses individual classification codes and weights for refuse collection, slurry pump and freight transport by road, respectively. Prices are updated every quarter, while weights are updated approximately every five years.

The weights reflect the cost shares of the total costs of performing refuse collection, slurry pump and freight transport by road.

Adjustment

Materials may be replaced over time. There is running quality control of new materials that are used in the The Cost index for refuse collection, slurry pump and freight transport by road.

No corrections are made besides from what has already been described under data validation and data treatment.