Selection within households in health surveys |
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Authors: | Maria Cecilia Goi Porto Alves Maria Mercedes Loureiro Escuder Rafael Moreira Claro Nilza Nunes da Silva |
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Institution: | I Instituto de Saúde. Secretaria de Estado da Saúde de São Paulo. São Paulo, SP, Brasil;II Departamento de Nutrição. Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brasil;III Departamento de Epidemiologia. Faculdade de Saúde Pública. Universidade de São Paulo. São Paulo, SP, Brasil |
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Abstract: | OBJECTIVETo compare the efficiency and accuracy of sampling designs including and
excluding the sampling of individuals within sampled households in health
surveys.METHODSFrom a population survey conducted in Baixada Santista Metropolitan Area, SP,
Southeastern Brazil, lowlands between 2006 and 2007, 1,000 samples were
drawn for each design and estimates for people aged 18 to 59 and 18 and over
were calculated for each sample. In the first design, 40 census tracts, 12
households per sector, and one person per household were sampled. In the
second, no sampling within the household was performed and 40 census sectors
and 6 households for the 18 to 59-year old group and 5 or 6 for the 18 and
over age group or more were sampled. Precision and bias of proportion
estimates for 11 indicators were assessed in the two final sets of the 1000
selected samples with the two types of design. They were compared by means
of relative measurements: coefficient of variation, bias/mean ratio,
bias/standard error ratio, and relative mean square error. Comparison of
costs contrasted basic cost per person, household cost, number of people,
and households.RESULTSBias was found to be negligible for both designs. A lower precision was found
in the design including individuals sampling within households, and the
costs were higher.CONCLUSIONSThe design excluding individual sampling achieved higher levels of efficiency
and accuracy and, accordingly, should be first choice for investigators.
Sampling of household dwellers should be adopted when there are reasons
related to the study subject that may lead to bias in individual responses
if multiple dwellers answer the proposed questionnaire. |
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Keywords: | Health Surveys methods Population Surveys Cluster Sampling Sampling Studies |
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