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 mapping of Danish household consumption has a long history dating back to 1897, when the consumption of Danish working‑class families was examined for the first time. In the period up to 1994, a series of different surveys of household consumption were conducted, often focusing on specific population groups. For example, in 1909 household accounts were prepared for urban workers, farm workers, smallholders and farmers, and in 1916 for civil servant families.

From 1971, dedicated household budget surveys were launched. The first survey covered the consumption of wage earners, while surveys from 1976 onwards included all private households. Since 1994, annual household budget surveys have been carried out for Danish households.

The previous data collection and estimation method was based on a three‑year dataset, where observations from year t–1, t, and t+1 were combined into a single sample. Data for t–1 and t+1 were subsequently converted into price and volume measures for the middle year, t. This design meant that only the data for t+1 were fully replaced each year, while data for t–1 and t were largely repeated with price adjustments. As a result, the method essentially functioned as a moving average, reducing the survey’s sensitivity to changes in consumption patterns.

From 2014 onwards, the sample was based on a two‑year period. Although this change did not eliminate the challenges related to price adjustments, it contributed to faster production of results and therefore to more timely and useful statistics. Today, annual data collection continues, but the sample consists of two consecutive years: t–1 and t. For the 2024 survey, this means that data from 2023 (t–1) and 2024 (t) are included. All observations are converted into price and volume measures at the 2024 price level to ensure comparability across the dataset.

Since the publication of the 2014 data, the Household Budget Survey has been based on a two‑year sample and on the ECOICOP nomenclature, which replaced the previously used COICOP1999 classification. To ensure comparability and continuity, data from 1994 to 2013 were recalculated in both current and constant prices according to the ECOICOP nomenclature.

Since 2012, the survey has been supplemented with consumption data in constant 2005 prices, enabling the analysis of volume developments over time. From the publication of the 2023 data onwards, Denmark has replaced ECOICOP with COICOP2018. To ensure comparability, data for 2015–2022 have been recalculated according to the new nomenclature. As a result, data can only be compared back to 2015.

COICOP2018 differs from ECOICOP in several important respects and includes, among other things, new consumption categories such as streaming services and mobile applications. The transition also involves a division of the former consumption group 12, leading to the establishment of a new main group, 13: “Personal care, social protection and miscellaneous goods and services.” This provides a more detailed and contemporary classification of household consumption.

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.