1. Country report Germany
Workshop “Integrating Global Census Microdata”
- Lisbon, 22 August 2007-
Andrea Harausz
My name is Andrea Harausz.
I work for the research data centre of the federal statistical office in Germany.
First of all I would like to say a big thank you to the mpc for the invitation to the workshop
and the great present and opportunity to attend the ISI 2007.
I am very pleased to present here on our progress in creating public use microdata files for IPUMS-Europe project.

2. Content
Microdata for the project “Integrated European Census Microdata” (IECM)
Delivered metadata
1971 census of the former German Democratic Republic
History
Characteristics and metadata
Preparation
Anonymisation
Outlook
My presentation will cover the following topics:
First I would like to say some words about the scope of the IPUMS Project for our country.
After that I will present the metadata that we were able to provide to the project.
The main emphasis of my presentation will be on the microdata of the 1971 census of the former GDR.
Finally I will give short outlook on the future work.
2007 August 22

3. Microdata for the IECM project
9 anonymized microdata files
2 censuses - Federal Republic of Germany
1970
1987
2 censuses - former German Democratic Republic
1971
1981
5 microcensuses - Federal Republic of Germany
1973
1982
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.
2007 August 22

4. 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.
2007 August 22

5. Available Metadata Enumeration forms Instructions to enumerators
GDR
c81
mc73
mc82
mc87
mc91
mc01
Enumeration forms
Instructions to enumerators
Codebooks for micro data
Occupation codes
Industry codes
Technical reports
Other
In the rows of this table you can see the most important metadata.
In the colums there are the microdata files to be contributed to the project
Recovering of these documents was easy for the younger microcensuses and the western german censuses, which were very accurately documented.
But for some files like the older microcensuses and the 1971 GDR census we had to investigate in several institutions like archives and regional statistical offices.
Today we have a nearly complete documentation to the microdata files.
2007 August 22

6. Available Metadata  Enumeration forms Instructions to enumerators
GDR
c81
mc73
mc82
mc87
mc91
mc01
Enumeration forms 
Instructions to enumerators
Codebooks for micro data
Occupation codes
Industry codes
Technical reports
Other
Here you can see the documentation we were able to provide to the project.
We were not able to find the instructions for enumerators and the industry codes for the 1971 gdr census.
We provided all our documentation in German.
The translation of them to English is made at the MPC. They already translated varios documents
2007 August 22

7. Available Metadata  Enumeration forms Instructions to enumerators
GDR
c81
mc73
mc82
mc87
mc91
mc01
Enumeration forms 
Instructions to enumerators
Codebooks for micro data
Occupation codes
Industry codes
Technical reports
Other
They are highlighted here.
After so much documentation the MPC also wanted to have some microdata of course.
We began with the anonymisation of the 1971 GDR microdata.
2007 August 22

8. 1971 census of the former GDR
History
Characteristics and metadata
Preparation of microdata
Anonymisation
The 1971 census microdata of the GDR.
First I would like to say some words to the history of the microdata of the 1971 GDR census.
2007 August 22

9. 1971 census of the former GDR
History
Central State Administration for Statistics of the GDR
Legal successor: Federal Statistical Office
Backup and documentation of data
Partly adaptation to the system of the 1987 census of the FRG
Release to the Federal Archive
Federal Archive
Data protected by data protection act
Archive law allows availability of data after 60 years
Special permission for the release of data for scientific purposes
The censuses of the GDR were conducted by the state administration for statistics of the GDR.
The microdata of the two last censuses from 1971 and 1981 were kept in a maschine readable format.
After the reunification of east an west germany the central state administration ceased to exist. Its legal succesor became the FSO. From then on the census data were in possesion of the fso.
After documentation and backup, the data were partly adapted to the system of the 1987 census of the FRG.
In 2000 the fso released the data to the federal archive where it is stored until it can be mada available to the public.
At the moment these data are protected by the data protection act and can be made available to the public 60 after the census year.
But The archive law allows the release of data for scientific purposes by the owner of the data, which is the fso.
2007 August 22

10. 1971 census of the former GDR
Characteristics and metadata
2 data files
Person file (demography, income, education, employment etc.)
Dwelling and building file (state of repair, occupancy, equipment 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.
2007 August 22

11. 1971 census of the former GDR
Preparation of microdata – Matching of data files
Matching by unique combination of variables in both files
Deletion of vacant dwellings and dwellings used for other purposes
Verification of 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
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.
2007 August 22

12. 1971 census of the former GDR
Anonymisation
Time
Drawing of a subsample
Geographic detail
Recoding
Sorting of households
 fully anonymised microdata = Public Use File
The concept is determined mainly by the following components:
Time – the data are almost 40 years old, what makes the reidentification of individuals very difficult, as every individual household changed its structure since than.
Drawing of a subsample, reducing georgraphic detail, recoding of variables and sorting of households.
The sum of these measures lead to a fully anonymised microdata file or a so called public use file.
2007 August 22

13. 1971 census of the former GDR
Sampling
Size: 25% household sample
Method: Systematic Random Sampling
Sorting of households by geographic variables
First household selected randomly from the first 4 cases
Then selecting every 4th household
As first step of the anonymisation:
We draw a 25% subsample,
a household sample, where persons in coll. dwelling are considered as households
The Sampling Method we used was systematic random sampling where we first household was selected randomly and than every 4th household systematically.
2007 August 22

14. 1971 census of the former GDR
Geographic detail
State (Nuts1)
Construction of a size of place variable
Categories:
less than 2 000
and more.
Berlin :
less than
and more.
In addition to the drawing of a subsample we reduced the geographic detail to the nuts 1 level which are the provinces or states.
Bob asked us to construct a size of place variable.
We constructed a variable named classes of municipal size with the following 6 categories.:
Goal was to create classes each of them covering about 25% of the population and each class has at least 3 municipalities per state.
2007 August 22

15. 1971 census of the former GDR
Recoding of variables
Principle: every value of a variable should have at least 3 observations in the original file
Recoded variables (top coding):
Age
Floor space of rooms in dwelling
Number of rooms in dwelling
Number of secondary residents in household
Regarding the recoding of variables, we determined that
each value of a variable should have at least 3 observations in the original file.
If a value has less then 3 observations, it has to be conbined with another value of the same variable.
Variables where recoding was necessary are:…
For all of them we applied top coding.
2007 August 22

16. 1971 census of the former GDR
Sorting of households
Random sorting of
Building in state
Dwelling in building
Adding new running number for
Household in dwelling
After removing the geographic variables the microdata file was still sorted by a systematic regional order.
To eliminate this additional information from the file, the buildings were sorted randomly in each state, the dwelling were sorted randomly in each building and
new running numbers for building in state, dwelling in building and household in dwelling were created.
2007 August 22

17. 1971 census of the former GDR
Public Use File
4,1 million persons
50,000 in collective dwellings
1,6 million households
104 variables
After applying all this anonymisation measures to the microdata we produced a Public Use File with
4,1 Million persons
1,6 Million households
104 variables
2007 August 22

18. Outlook
1970 .
1987
1973
1971
1981
1980´s
1970´s
1990´s
1982
1991
2001
After having finished the 1971 census, we are planning to create the next public use files for the 1981 gdr census and afterwards for the 1987 microcensus.
2007 August 22

19. Thank you! andrea.harausz@destatis.de www.forschungsdatenzentrum.de
2007 August 22