Philippines Sample Design

Quarterly Social Weather Surveys

(within which the Mental Stigma Module will be implemented)

 1.   Location

The Social Weather Surveys divides the Philippines into four major study areas: National Capital Region (NCR), Balance Luzon (outside NCR), Visayas and Mindanao .

 2.   Timetable

All the four study areas are covered simultaneously within two calendar weeks.  Fieldwork is usually implemented in the 2^nd month of a quarter.

 3.   Respondents

The survey has as respondents randomly-chosen Filipino voting-age adults, 18 years old and above.

 4.   Sampling Method

Sample Sizes and Error Margins.  Each of the study area has a sample size of 300, for a total sample size of 1,200 Filipino voting-age adults for a error margin of +/- 2.83% at the 95% confidence level, assuming a simple random sampling design. 

 5.   Weighting Procedure

To yield representative figures at the national level, census-based population weights are applied to the survey data. The weight projection is computed by dividing the projected population in the area by the sample size of the same area.  Appropriate projected factors are applied so that original population proportion are reflected in the data tables using this formula.

                                                     Population

                    Projection factors   =    ------------------------

                        (Weight)                  No. of Interview

 (Note: Details on sampling scheme, research methodology and weighting factors are provided in a separate document)

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Last updated: 6 September 2005
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