8.
Information retrieval
How can a user find out what data are available on a specific
topic? On the file level datasets are described according to the
earlier mentioned study description scheme.
These descriptions are used to publish catalogues with
information on the broad topics of the datasets, with a listing of
the number of cases and the number of variables and with some
details on what population is studied in every dataset. This
catalogue will allow users to get a good overview of what is
available in the archive.
If indices are included, the catalogue can be used for simple
searches (2).
As the data archive is dedicated to work with machinereadable
information, it should not be a surprise that its own information
systems are also fully automated.
Many archives
have an information retrieval system on computer available.
This system will allow more elaborated searches on the various
information items in the study description scheme (3).
Next to the systems working on the file level some archives have a
system on the level of the variables in the files. In these
systems every single variable in each dataset is documented in
such a way that it can be found in a computer search.
Given the enormous amount of work that is involved with the
documentation on the variable level, this type of documentation is
usually limited to a subset of the holdings.
The European data archives joined forces to offer virtually
integrated data catalogues via Internet.
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