The ELSI-Brazil sample was designed to be representative of the Brazilian population aged 50 and older. Data from the 2010 National Census carried out by the Brazilian Institute of Geography and Statistics (IBGE) were used for sampling design. The estimated sample size was 10,000. This sample size, at a level of significance of 95% and an effect sample design of 1.5, allows an estimated prevalence of 1% with a sample error of 0.25%, or a prevalence of 5% with a sample error of 0.55%. For the same level of significance and effect sample design, it is also possible to identify differences of 2.2% for a prevalence of 10% with the power of the test equal to 80%.
Selection of municipalities
The municipalities were allocated to four strata depending on their population size. To decide the size of the municipality and the number of municipalities allocated to each stratum, the Lavallée & Hidiroglou’s (1988) method of stratum construction was performed, using the R stratification package. The four strata were categorized as follows: first stratum (≤ 26,700 inhabitants from 4,420 municipalities); second stratum (26,701 – 135,000 inhabitants from 951 municipalities); third stratum (135,001 – 750,000 inhabitants from 171 municipalities); fourth stratum (> 750,000 inhabitants from 23 municipalities). For the first three strata i.e. municipalities up to 750,000 inhabitants, the sample was selected in three stages. In the fourth stratum, that included the largest municipalities, the sample selection was done in two stages.
Figure 1 and Table 1 show the list of selected municipalities by geographic region and state.
Figure 1 – ELSI-Brazil: selected municipalities by state and Federal District.
Table 1 – ELSI-Brazil: List of selected municipalities by geographical region and state.
|São José de Ribamar|
|São Raimundo do Doca Bezerra|
|Limoeiro do Norte|
|Rio Grande do Norte||Natal|
|Bahia||Feira de Santana|
|Southeast||Minas Gerais||Belo Horizonte|
|Espírito Santo||Cachoeiro de Itapemirim|
|Rio de janeiro||Duque de Caxias|
|Rio de Janeiro|
|São Pedro da Aldeia|
|São Bernardo do Campo|
|São Caetano do Sul|
|Santa Maria do Oeste|
|São José dos Pinhais|
|Rio Grande do Sul||Canoas|
|São Paulo das Missões|
|Midwest||Mato Grosso do Sul||Campo Grande|
|Mato Grosso||Chapada dos Guimarães|