Page 226 - Invited Paper Session (IPS) - Volume 1

IPS142 Jorge L. V. V. et al.
example information about rented dwellings that is stored in the declarations
of the Tax Agency) in the data sources used that would help to increase the
quality of this variable.

6. Other elements
6.1 Inclusion of other variables
The use of administrative sources opens the door to the incorporation of
new variables, either because of the availability of new sources, or because of
the possibility to exploit them in another way.
A traditional Population and Housing Census uses the questionnaire as the
instrument for collecting information. In this situation, the main constraint
when designing any census questionnaire is that it should be shorter and
easier to understand better, because this will achieve a better quality of
response. However, in the case of a register-based Census this limitation
disappears; therefore, it can cover concepts that are difficult to include in a
questionnaire and in many cases very demanded. Some examples of the
variables that could be incorporated in the 2021 Spanish Census are:
• Information about property of vehicles, from Traffic institution
• Fertility, number of children born in the previous years
• Data on other owned dwellings, based on Tax Agency information
and Cadastre
On the other hand, one of the strengths of a register-based census, which
has not been sufficiently exploited yet, is the possibility of incorporating new
context variables, that do not refer to a concrete individual (both because of
legal restrictions or because of quality issues for individual data), but to the
average or total of his/her enumeration area. Some examples of variables of
this type that we could incorporate are: income level, electrical consumption
or presence of green areas.

6.2 The survey
Maybe one of the main points of improvement of the Census is not the
quality of the file that can be produced, but the shortcomings of information
that it is not available in the different records that we use. The lack of certain
information in relation to commuting (not mandatory but highly demanded)
is an important lack. Furthermore the need for more demographic
characteristics like second generation of immigrants, more reliable
information about household members and better information about
households is another handicap.
For all these reasons, and in order to complete the Census project, we are
planning to conduct an ad-hoc survey that would target about 1% of
households and would answer these and other questions.

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