Country report Germany III. Workshop ‘Integration European Census Microdata’ Barcelona, July 9, 2008 Markus Zwick, Research Data Centre Federal Statistical Office Germany after our introduction of the paticipants data acces, data use, anomysed data and so on explain – erklären teaching statistic

Research Data Centers (RDC) in Germany RDC of the Federal Statistical Office RDC of the Federal Employment Agency at the Institute for Employment Research RDC of the German Federal Pension Insurance Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

RDC of official statistics interface organisation between data producers and empirical science consulting and service for the use of official microdata possibility for access to microdata with low anonymisation level Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

RDC: Advantages for the data producer More research on our own data Higher data quality Greater network on researchers More competence on data and research knowledge International acceptance of RDC researcher Better reputation of German research Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

delete direct identifier Level of Anonymisation Degree of confidentiality delete direct identifier anonymisation method stronger anonymisation method de-facto anonymised microdata fully anonymised microdata complete microdata confidential microdata Degree of analysis potential Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

Possibilities for microdata access - de-facto anonymised microdata (Scientific Use Files) - fully anonymised microdata (Public Use Files and Campus Files) - Visiting Researcher‘s Desktop - Controlled Remote Data Processing (Remote Execution) - Special Data Processing Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

CAMPUS-Files as special Public Use File Target Application for university teaching, training in use microdata and simultaneous qualification by use a statistical programm like SAS, Stata or SPSS Conception Small sample size and less variables primary not for scientific use Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

German Microdata as Public Use File for the IECM project nine anonymised microdata files - census 1970 and 1987 for the Federal Republic of Germany - census 1971 and 1981 for the former German Democratic Republic - five micro censuses for the Federal Republic of Germany; 1973, 1982, 1987, 1991, 2001 Germany will contribute to the IPUMS-Europe project with the creation of nine public use microdata files for the following statistics: The two last censuses of the former GDR and the FRG. In addition to the censuses we will create puf of 5 microcensuse of FRG. Our microcensus is a 1 % household sample survey carried out every year. with a very broad range of variables. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 8 8

German Microdata for the IECM project 1970 . 1987 1973 1971 1981 1980´s 1970´s 1990´s 1982 1991 2001 This picture is to visualize the distribution of the microdata files over time. The grey-coloured symbols show the population censuses. The yellow ones the microcensuses. The microdata files are distributed over 4 decades. All these microdata were found in the statistical offices and archives in a machine-readable format. Which was not the case with the metadata. Almost all documentation, if it survived, was only available as paper copy. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 9 9

Census of the former GDR 1971 Characteristics and metadata two data files - Person file (demography, income, education, employment etc.) - Dwelling and building file (state of repair, occupancy, etc.) 16,4 mio. persons, 6,2 mio. households, 6 mio. dwellings metadata no codebooks at FSO and Federal Archive Archives of regional statistical offices in the former GDR states (Field of study, occupation codes) For this purpose we requested the microdata file for the 1971 census from the federal archive: we received two files A person file and a dwelling and building file. The person file contain information on demography, income, education, employment and the household structure. The dwelling file provide information on the state of repaire of the building, the occupancy status, the equipment of the dwelling with heating, hot water supply and sanitary equipment. We have in total 16,4 million persons, 6,2 million households and 6 million dwellings in the datafiles. Concerning the metadata for this census, we had difficulties to find some. The fso and the federal archive had almost no documentation on this census. We searched documentation in libraries and archives of regional statistical offices in the former estern German states. After having found enough documentation to understand the microdata we began with the matching of the two microdata files. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 10 10

Census of the former GDR 1971 Collecting Data - matching by unique combination of variables in both files (person file and dwelling file) - anonymisation by local suppression and by top and bottom coding - systematic random draw to create a 25% sample - available Public Use File include 4,1 Mio person in 1,6 Mio household with 104 Variables They were matched by a unique combination of variables existent in both files. We verified the matching method by comparison of certain variables existent in both files: -number of principal residents in 1st household -number of children under age 17 in 1st household In the case of a succesful matching the values of these variables should be identic in both files. The first variable indicated a succesfull matching the second showed differences in the two files. These differences appeared only in case of households with children in the age of 17. We suppose that these children were considered in one file as children under age 17 and in the other as children over age of 17. We can assume that the matching of the two data files was succesful. After matching the two data files we developed an anonymisation concept for the data. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 11 11

The political discussion about the census in the eighties in Germany - great social opposition against the census in 1983 - refusal after the decree of the Federal Constitutional Court - implementation of an ‘informational self-determination‘ as an civil right in the german law - census execution in 1987 For this purpose we requested the microdata file for the 1971 census from the federal archive: we received two files A person file and a dwelling and building file. The person file contain information on demography, income, education, employment and the household structure. The dwelling file provide information on the state of repaire of the building, the occupancy status, the equipment of the dwelling with heating, hot water supply and sanitary equipment. We have in total 16,4 million persons, 6,2 million households and 6 million dwellings in the datafiles. Concerning the metadata for this census, we had difficulties to find some. The fso and the federal archive had almost no documentation on this census. We searched documentation in libraries and archives of regional statistical offices in the former estern German states. After having found enough documentation to understand the microdata we began with the matching of the two microdata files. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 12 12

Census of the FRG in 1987 - 63 Mio. person, 27 Mio. households with 210 variables - the census include a occupation, a building and a dwelling census - the Public Use File is planned as an 1% systematic random sample - anonymisation by local suppression and by top and bottom coding For this purpose we requested the microdata file for the 1971 census from the federal archive: we received two files A person file and a dwelling and building file. The person file contain information on demography, income, education, employment and the household structure. The dwelling file provide information on the state of repaire of the building, the occupancy status, the equipment of the dwelling with heating, hot water supply and sanitary equipment. We have in total 16,4 million persons, 6,2 million households and 6 million dwellings in the datafiles. Concerning the metadata for this census, we had difficulties to find some. The fso and the federal archive had almost no documentation on this census. We searched documentation in libraries and archives of regional statistical offices in the former estern German states. After having found enough documentation to understand the microdata we began with the matching of the two microdata files. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 13 13

Microcensus for the FRG - annual 1% revolving household sample with obligation to give information by law - 800.000 person, 380.000 households with nearly 750 variables - Scientific Use File as 70% subsample for researcher in Germany For this purpose we requested the microdata file for the 1971 census from the federal archive: we received two files A person file and a dwelling and building file. The person file contain information on demography, income, education, employment and the household structure. The dwelling file provide information on the state of repaire of the building, the occupancy status, the equipment of the dwelling with heating, hot water supply and sanitary equipment. We have in total 16,4 million persons, 6,2 million households and 6 million dwellings in the datafiles. Concerning the metadata for this census, we had difficulties to find some. The fso and the federal archive had almost no documentation on this census. We searched documentation in libraries and archives of regional statistical offices in the former estern German states. After having found enough documentation to understand the microdata we began with the matching of the two microdata files. Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de 14 14

Microcensus as Public Use File - microcensus Public Use File for 1973, 1982, 1987, 1991 and 2001 - 35% subsample - ca. 300 variables - anonymisation by local suppression and by top and bottom coding Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

Multiple source mixed mode model Federal Statistical Office Germany, Dr. Markus Zwick www.forschungsdatenzentrum.de

Country report Germany III. Workshop ‘Integration European Census Microdata’ Barcelona, July 9, 2008 Markus Zwick, Research Data Centre Federal Statistical Office Germany after our introduction of the paticipants data acces, data use, anomysed data and so on explain – erklären teaching statistic