[Master sample and geoprocessing: technologies for household surveys].
OBJECTIVE
To reduce cost and time associated with household sampling process and to assess the feasibility of shared use of address data file of census enumeration areas in several epidemiological surveys using updated information from the National Survey of Households (PNAD).


METHODS
Address data file comprising 72 census enumeration areas was kept as primary sampling units for the city of S o Paulo. During the period 1995-2000, three distinct household samples were drawn using the two-stage cluster sampling procedure. Geographic Information System (GIS) technology allowed delimiting boundaries, blocks and streets for any primary sampling unit and printing updated maps for selected sub-samples.


RESULTS
Twenty-five thousand dwellings made up the permanent address data file of the master sample. A cheaper and quicker selection of each sample, plus gathering information on demographic and topographical profiles of census enumeration areas were the main contribution of the study results.


CONCLUSIONS
The master sample concept, integrated with GIS technology, is an advantageous alternative sampling design for household surveys in urban areas. Using the list of addresses from the PNAD updated yearly, although limiting its application to the most populated Brazilian cities, avoids the need of creating an independent sampling procedure for each individual survey carried out in the period between demographic censuses, and it is an important contribution for planning sampling surveys in public health.
da Silva
Nilza Nunes
NN
Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brasil. nndsilva@usp.br
da Cunha
Tarcisio Neves
TN
Quintanilha
José Alberto
JA
D019352:Censuses; D003625:Data Collection; D005191:Family Characteristics; D040362:Geographic Information Systems; D006306:Health Surveys; D006801:Humans; D012494:Sampling Studies