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Metadata for Official Statistics

Series: Microcensus (MZ)

Abstract

The Microcensus is an official representative statistic on the population and the labour market in Germany. With a sampling fraction of 1% of the population, it is the largest annual household survey in Europe. The Microcensus has been conducted in West Germany since 1957 and in the new federal states (Bundesländer) since 1991. The population of the Microcensus comprises all persons in Germany who have the right of residence. Starting with the 2020 survey year, in addition to the Labour Force Survey (LFS), which has already been integrated since 1968, the Survey on Income and Living Conditions (SILC), which was previously collected separately, is also integrated into the Microcensus. Furthermore, starting in 2020, the Labour Force Survey is supplemented by a repeated interview during the same year. Starting with the 2021 survey year, the Survey on Information and Communication Technologies (ICT) Usage in Households and by Individuals, is also integrated into the Microcensus.


The survey programme of the Microcensus consists of a core programme that remains the same in each round. It furnishes basic socio-demographic data and facilitates the ongoing monitoring of the labour market. In addition to the variables in the core programme, which are collected annually, further information on topics such as education and training, current and previous job, and labour market participation is collected within the framework of supplementary programmes with varying sampling fractions. Other international additional programs occur on a rolling basis or in the form of ad hoc modules.

Geographical Coverage

Germany

 


Organization

Due to the federal organization of the German statistical system, the federal statistical office cooperates with the statistical offices of the Länder. The planning and preparation of the Microcensus is carried out by the Federal Statistical Office. The statistical offices of the Länder are responsible for conducting surveys and preparing the data.


Universe

All persons in Germany who have right of residence, living in private households or collective households, at their main and secondary residence. (The survey population does not include members of foreign armed forces or the diplomatic corps and their families. Because the Microcensus uses an area sampling design, homeless persons have no chance of inclusion in the survey.)


Sampling

Sampling method

Single-stage stratified cluster sampling (since 1972)

Sampling fraction

Core program: 1 % of the residential population

2005-2011: Ad hoc modules 0.1 %; EU labour force survey structural variables 0.1 %

2012-2019: Ad hoc modules 0.1 %; EU labour force survey structural variables 1 %

2020: Labour Force Survey (LFS) maximum 45 % of total sample; Statistics on Income and Living Conditions (SILC) maximum 12 % of total sample (collected separately up to and including 2019).
Beginning in 2021: Labour Force Survey (LFS) maximum 45 % of total sample; Statistics on Income and Living Conditions (SILC) maximum 12 % of total sample (collected separately up to and including 2019); Information and Communication Technologies (ICT) in households maximum 3,5 % of total sample (collected separately up to and including 2020).

Sampling frame

Up to 2015 the master sample for the old federal states was based on results of the 1987 Census of Population and for the new federal states and East Berlin on results from the "Bevölkerungsregister Statistik 1990" (statistics derived from the central population register) of the German Democratic Republic (GDR). From 2016 onwards the 2011 Census serves as selection basis for the Microcensus. The master sample is updated annually by taking new construction activities into account. Since 1990, updating has been carried out by drawing a new-construction sample from building activity statistics. In the 1972–1989 rounds of the Microcensus, the supplementary sample was realised either on the basis of interviewers' reports of new construction activity in the sampled municipalities or on the basis of zoning maps.

Primary sampling units

The sampling districts (primary sampling units) are artificially delimited areas (clusters) comprising, as a rule, neighbouring buildings; in the case of larger buildings, only one building, or a subdivision thereof, is included. Up to the 1989 Microcensus, a sampling district comprised, on average, 23 dwellings. To enhance regionalisability, the average size of the sampling districts was reduced in 1990. Since then, the average sampling district comprises 9 dwellings. The target size for sampling districts in the collective-household building stratum is 15 persons.

Partial rotation

1974-1977: Rotation halves remained in the sample for two years; each year half of the sampling districts were replaced.

1977-2019: Each sampling district remains in the sample for four years. Each year, a quarter of the sampling districts are replaced by newly introduced sampling districts. 

Since 2020: Sampling districts can be surveyed up to four times. Each year, approximately 30 percent of the sampling districts drop out, while a correspondingly large proportion rotate into the survey. Private households in sampling districts that are part of the LFS subsample are surveyed repeatedly during the year (surveyed repeatedly for two consecutive quarters, then not surveyed for two quarters, then surveyed again for two consecutive quarters). These households thus rotate out of the current sample more quickly. Institutional households in LFS sampling districts are interviewed only in the first and third survey waves and in the fourth if it falls in a first calendar quarter.

Households and persons moving out of the sampling district are not followed but rather replaced by households and persons moving into the sampling district. The Microcensus is therefore a repeat survey with partial overlapping of sampling units. The rotation quarter to which a respondent belongs is not identifiable in the basic and regional Scientific Use Files (SUFs). Since 1996, it has been legally possible to aggregate the cross-sectional data to form a panel data set. Two panel data sets are available as SUFs for panel analyses: 1996-1999 and 2001-2004. A new procedure for the subsampling and time-consistent identifiers allows researchers to independently create panel files from the Scientific Use File 2012 onwards (see also: Microcensus Scientific Use Files from 2012 onward as a Rotational Panel). As a qualification, it needs to be mentioned that a new sample was drawn in 2016, so that panel files can be created only from 2012 up to 2015. Furthermore, panel files from 2016 onwards are limited to the period up to 2019, as the Microcencus and other household statistics have been converted to a fundamentally new system from 2020 onward.

 


Data Collection

Until and including 2019, the surveys were usually collected via personal interviews (either paper-and-pencil interviewing (PAPI) with the help of a paper-based questionnaire or – since the 1990s – computer assisted personal interviewing (CAPI) using a laptop). CAPI has been universally used since the 2005 Microcensus. Some respondents complete a self-administered questionnaire or participate via telephone interview (Computer Assisted Telephone Interview, CATI). Since 2020, the survey has been conducted increasingly by methods without face-to-face contact. The new option of participating in the survey via online form (Computer Assisted Web Interview, CAWI), which was introduced in 2020, is also frequently used.

Sampled households and their members are obliged by law to provide information for the Microcensus. However, response to some items is voluntary. The Microcensus is a household survey. In other words, all members of the household are interviewed in person, or one adult member responds on behalf of the other household members, including all minors (proxy interview). The data collected are processed by the statistical offices of the federal states and aggregated into a single data set by the Federal Statistical Office. Further processing steps are also carried out centrally by the Federal Statistical Office.


Anonymization

Guidelines for the Factual Anonymization of Particular Statistical Microcensus Information (From the appendix to the standard contract of the Federal Statistical Office regarding the dissemination of Microcensus data)

  1. In accordance with the Microcensus Act, direct identifiers, such as personal identification numbers, names, addresses, telephone numbers, or any other official numbers that permit identification of persons from the data may not be distributed. Therefore, they may not be contained in the data file.
  2. The dataset must be transmitted in an unsystematic order.
  3. Only a randomly generated 70% subsample may be distributed.
  4. The only direct regional data to be given are those of the respective German state.
  5. In the "community size" category, no individual community with a population of less than 500,000 may be identifiable. If there are multiple communities in the same category, they must together comprise at least 400,000 inhabitants in every German state.
  6. The citizenship or nationality of groups in the Federal Republic of Germany with less than approximately 50,000 persons are not to be identifiable.
  7. In its univariate distribution within the statistical population, each category trait must include an aggregate of at least 5,000 cases. If this precondition is not met, then a statistically appropriate simplification or aggregation is needed in order to reach the required number of cases.

To item 3: The Microcensus Scientific Use File (SUF) is a de-facto anonymised 70 percent subsample of the households in the Microcensus. Until 2011, households or dwellings were primary sampling units of the Microcensus, with all persons of a selected household or dwelling being included in the sub-sample. Dwellings were drawn in the survey years in which the 4-year supplementary programme on housing (1998, ..., 2010) was carried out. The basis for the systematic random selection is the original data of the Federal Statistical Office. From 2012, the primary sampling units for the sub-sample are the sampling districts within a rotational quarter.


Legal Basis

Federal Statistics Act (BStatG)

Surveys for official statistics are regulated by the Federal Statistics Act. The Federal Statistics Act also regulates the dissemination of data to the scientific community. The official surveys from the 1950s to the present cover a timeframe that can be divided into several periods with regard to the respective applicable legal laws (information on periods before 1950 see: Allgemeines Statistisches Archiv 88 (4): 473-486).

Microcensus Law and Legislative Decrees

For the implementation of specific federal statistics, an additional specific legal principle is needed. The legal basis of the Microcensus is the Microcensus Law. Additional programs, for example, can be included through legislative decrees. In the course of the history of the Microcensus since 1957, there have been several Microcensus laws and legislative decrees. For the development phases of the Microcensus, see Lüttinger/Riede, 1997 [.pdf] and Emmerling/Riede 1997 [.pdf].

 Currently valid Microcencus Law

  • An antichronological list of amendments to the Microcensus Law and legislative decrees can be found on the following page (as of 06.11.2018).

EU Regulations

Additional information may be collected on the basis of European Community regulations. The Metadata Report Part 1 on the Microcensus (Section 1.2) contains a list of the relevant regulations.


Weighting

Extrapolation in the Microcensus follows a two-stage procedure. The first stage – correction, or compensation, for non-response – entails extrapolating from the net sample of successfully surveyed households to the gross sample of all households on the basis of the design weight. In the second stage – adjustment – the weighted sample is adjusted to conform to benchmark figures from the intercensal population estimates (laufende Bevölkerungsfortschreibung). Depending on the methods used, the two-stage procedure yields different extrapolation factors for the individual survey years.


Comparability over Time

In 2005 the mode of data collection was changed and data was no longer collected during a set timeframe but during the entire year. Due to this change results from 2005 onward are only partially comparable to prior studies. To improve the implementation of the ILO Labour-Force-Concept since 2005 the questions on labour force participation as well as the field work were adapted. Comparisons over time thus might be influenced by changes in methodology (For more information see: Statistisches Bundesamt, 2012: Methodeninformation. Mikrozensus und Arbeitskräfteerhebung: Ergebnisse zur Erwerbstätigkeit ab dem Jahr 2011. Wiesbaden [.pdf]).

Since a new sample was drawn for the 2016 Microcensus, comparability with previous years is limited.

Due to fundamental methodological changes and problems with data collection in 2020 (and to a lesser extent also in 2021), comparability with previous years is limited.

Further information can be found on the pages for the respective Microcensus study as well as in the Microcensus quality reports.


Spatial Comparability

The integrated EU-Labour Force survey (LFS) the Survey on Income and Living Conditions (SILC), which has been integrated since 2020, and the Survey on ICT Usage in Households and by Individuals, which has been integrated since 2021, allow for comparisons with other EU member states. The Microcensus data allows for comparisons at the level of federal states (Bundesländer) as well as more fine grained regional units.


FAQ

Further information about the Microcensus is available on the websites of the Federal Statistical Office (Was ist der Mikrozensus?) and the Research Data Centres of the Federal Statistical Office and the Statistical Offices of the Länder.

References

Statistisches Bundesamt: Qualitätsberichte zum Mikrozensus (ab 2006)

Statistisches Bundesamt: Erläuterungen zum Mikrozensus.

Statistisches Bundesamt: Fachserien zum Mikrozensus:

  • Haushalte und Familien, Fachserie 1 Reihe 3 (online ab Mikrozensus 2002)
  • Bevölkerung mit Migrationshintergrund, Fachserie 1 Reihe 2.2 (online ab 2005)
  • Stand und Entwicklung der Erwerbstätigkeit in Deutschland, Fachserie 1 Reihe 4.1.1 (online ab 2003)
  • Beruf, Ausbildung und Arbeitsbedingungen der Erwerbstätigen in Deutschland, Fachserie 1 Reihe 4.1.2 (online ab 2003)
  • Bestand und Struktur der Wohneinheiten, Fachserie 5 Heft 1 (online ab 2006)

Forschungsdatenzentren der Statistischen Ämter des Bundes und der Länder: Erhebungsunterlagen (ab Mikrozensus 1973)