Affiliations: National Statistics Institute, Madrid, Spain
Note: [] Corresponding author: Antonio Argüeso, National Statistics
Institute, Madrid, Spain. E-mail: antonio.argueso.jimenez@ine.es
Abstract: The population and housing census 2011 in Spain has followed a new
approach. Instead of an exhaustive door-to-door enumeration of the population,
it has been conceived as a combination of two elements: registers and survey.
The overall cost of the census, 85 million euros, represents 20% of the cost
of a classical census. We can benefit from the existence of a Population
Register of high quality in Spain. Taking this register as its backbone, a
census file was created using all available administrative registers
(tax collection agency, social security, vital statistics...). These
registers were used to provide, for every person, a measure of proof of
residence. But some 2.2% of the population remained as being of
doubtful residence in the registers, because that there was not
sufficient evidence in registers to count them. These people were grouped into
homogeneous clusters (region, sex, age, citizenship...) and were counted in
the census using weights (called count factors) obtained from the
survey. This survey was actually the second element of the census. It consisted
of a fieldwork operation including a classical building census that enabled
geo-referencing every building and a sampling survey addressed to 10% of the
population, in order not only to get those weights but also, and mainly, to
provide characteristics of persons and dwellings. This "10% survey" was
collected using a sequential multi-channel method, thus promoting the Internet
as first option (38% of the questionnaires were collected through this
channel). Eventually, the census, as a product, is the mixture of two
components: a weighted census file containing around 47 million
registers but only with a few variables for every person (those contained in
the population register) and a file containing many variables, the ones
collected in the questionnaires, but only for 4.2 million people. This system
has similarities with censuses based in long and short forms. Providing
consistency between detailed data coming from the survey and the main figures
coming from the weighted census file has proved to be a challenge. Some
inconsistencies show up and consequently, more than ever, the approach used for
dissemination and explanation to users becomes crucial.
Keywords: Administrative registers, multi-channel surveys, population register
