Comparability

Comparability - geographical

The calculation of the Household Budget Survey is based on international recommendations and therefore there is a good correlation with figures from countries of the European Union. Eurostat publishes every five years each country's Household Budget Survey in their publication databases.

Comparability over time

The first time Danes’ consumption was recorded was in 1897, when the consumption of Danish working-class families was surveyed. Up until 1994, various surveys of Danish consumption were carried out, often focusing on different population groups. For example, in 1909 household accounts were compiled for urban workers, farm workers, smallholders and farmers, and in 1916 for civil servant families. From 1971, household budget surveys have been conducted. In 1971, the focus was on the consumption of employees, and from 1976 onwards, the surveys have covered the consumption of private households.

Since 1994, annual surveys of the private consumption of Danish households have been conducted. The data collection method was based on collecting data over three consecutive years, which were combined into a sample. Data from year t − 1 and t + 1 were adjusted in terms of price and quantity to match the level of the middle year, t. A disadvantage of this model was that only the data for year t + 1 were updated and adjusted to the middle year, giving the survey the character of a kind of moving average. Switching to a two-year sample from 2014 did not resolve this issue, but it did accelerate the production of data, making the survey more current and relevant. The method remains based on annual data collections. The sample now consists of year t − 1 and t. For example, the 2023 sample consists of data from 2022 (t − 1) and 2023 (t), which are adjusted in terms of price and quantity to the price level of 2023.

Since the publication of the 2014 figures, the Household Budget Survey has been based on a two-year sample and the ECOICOP nomenclature instead of COICOP1999. To ensure comparability and continuity, data from 1994 to 2013 have been recalculated in both current and constant prices according to the ECOICOP nomenclature.

Since 2012, the survey has been supplemented with data in constant 2005 prices, making it possible to track volume trends over time.

From the publication of the 2023 figures, Denmark has replaced ECOICOP with COICOP2018. To ensure comparability and continuity, data from 2015 to 2022 have been recalculated according to COICOP2018. As a result, data can now only be compared back to 2015.

COICOP2018 differs in several important respects from ECOICOP. COICOP2018 is an updated version developed by the United Nations and includes new consumption categories, such as streaming services and mobile apps. Consumption group 12 ‘Miscellaneous goods and services’ has been split into two distinct groups as part of the transition to the COICOP2018 nomenclature. This split has led to the creation of a new main group, namely group 13 ‘Personal care, social protection and miscellaneous goods and services,’ which enables a more detailed and systematic recording of household consumption expenditures.

Coherence - cross domain

The classifications and definitions used are aimed to be as comparable as possible with the national accounts. But the methods, etc., in these two kinds of statistics are very different. The classification of consumption is based on the international COICOP5 classification, which is also used in compiling price indices. It is difficult to conduct comparisons with the general population statistics and other register-based statistics, as the household definition in the survey is different: In the survey the household definition is the economic unit, which is decided by the household members themselves, while in the general population statistics the household definitions are derived from the administrative registers-based information.

These statistics are also used in the experimental statistics Income and consumption distribution in the household sector.

Coherence - internal

The Household Budget Survey is based on three data sources, interviews, accounting and registers. A great deal of work is done to ensure that the register information used is consistent and valid in relation to linking it to the interview and the accounting information.