Stigma In Global Context: Mental Health Study
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Brazil Sample Design

Brazilian academic survey

         The first Brazilian academic social survey: Pesquisa Social Brasileira – PESB (2002)

         National survey of Opinion: from June 20st to October 30th

         Full probabilistic sample

         Sample size: 2365

         Financed by Ford Foundation

         Organizers: Alberto Carlos Almeida, Zairo B. Cheibub,

PESB sample design

The study employs a three stage stratified probability sample of Brazilian adults. 

         In the first stage, 102 primary sampling units (PSU), or municipios, were selected probability proportional to size (PPS). 

         In the second stage, 280 secondary units (census tracts) were selected PPS within each of the PSUs. 

         In the third stage, households were selected at random with one adult respondent being selected at random too.

         Each PSU consists of a single município as defined by IBGE. For the 1996 Contagem, IBGE divided Brazil into 5 census region with 27 states and 5507 municípios.

          27 of these municípios were selected with certainty as self-representing PSUs and 75 as non self-representing PSUs. The self-representing PSUs are state capitals. 

         PESB represents the general population. The sample was designed to be representative of the 5 census regions and state capitals. 

         To reduce costs of travel all municípios of regions Norte and Centro-Oeste, with less than 20,000 inhabitants, were excluded. This comes to a total of 11.9 percent of the municípios and 3.1 percent of the population excluded from the sample. The total effective sample comes to 2010 respondents.

         The PESB employs a two-stage stratification scheme where PSUs first are explicitly stratified, or grouped, by region and type of município (state capital/or not).

         Moreover, the PESB employs implicit stratification.

         Within regions, all non-self representing PSUs were further stratified by three additional variables: (1) HH population size; (2) urbanization rate; and (3) literacy rate. 

         In the sorting of PSUs using the implicit stratification variables, we used alternating ascending and descending orders in successive groups.

         The explicitly stratify the sample consider the five Grand regions as defined by IBGE: (1) Sul; (2) Sudeste; (3) Nordeste; (4) Centro-Oeste; and (5) Norte.

         Furthermore, to increase the users ability to analyze results for the smaller regions, the PESB employs a disproportionate sample design, sampling the three smallest regions (Centro-Oeste, Norte, Nordeste, and Sul) at higher rates and the largest region (Sudeste) at a lower rate.

         Finally, we stratified PSUs by whether the sampling unit was a capital or not. As stated in the previous section, we decided on this design based upon the potential importance of state capitals in explaining socio-political differences within Brazil .

PESB sample design – Logic of Stratification

Table 4: Household Distribution by the 5 Census Regions

Region

# of Households

Proportion

Proportional Sample

Error

Disprop.Sample

Error

Centro-Oeste

1,678.714

0.044

88

15%

120

13%

Norte

1,484.299

0.039

78

16%

100

14%

Nordeste

7,352.564

0.191

384

7%

420

7%

Sudeste

12,831.515

0.333

670

5%

540

6%

Sul

5,277.372

0.137

276

8%

320

8%

State Capitals

9,862.872

0.256

515

6%

510

6%

Total

38,487.336

1,000

2,010

3%

2,010

3%

          The sample design of SGC-MHS, will be a subs-sample of PESB 2002 sample frame.

PESB 2004 and SGC-MHS

         In order to reduce the overall cost of this year´s PESB, a smaller sample will be selected - 1200 interviews instead of 2500  

          The sample will be selected from the original master sample selected in 2002 - 102 city sample.  

          Specifically, the number of interviews for self-selecting PSUs will be reduce by 1200/2500 and the number of NON-self-selecting PSUs will be reduce by 1200/2500.

Plans for pre-fielding and fielding activities

 

Mar

Apr

May

June

July

Aug

Sep

Oct

Nov

pre-fielding activities

discussion & preaparation of questionnaire

pilot testing ( a small pilot)

preparation of field work information

training of interviewers

X

X

 

 

 

 

 

 

 

fielding activities

data collection

supervision

quality control

 

 

X

X

X

 

 

 

 

Pos-fielding activities

data entry

data cleaning

preparation methodological reports

 

 

 

 

X

X

X

X

X

 

 

 

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Last updated: 6 September 2005
Comments: sgcmhs@indiana.edu
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