The usual sampling that opinion surveys/market research employ was slightly modified to fit the quarantine situation during the conduct of this survey. However, all possible quality assurance measures were performed to ensure the validity of the survey.
- In each city, sample barangays were selected via simple random sampling, i.e., barangays have equal chances of being selected.
- In each sample barangay, the field interviewer who resides nearest to the sample barangay was tasked to recruit potential survey respondents by securing the household head’s mobile number and his/her agreement to participate in a telephone survey. An interval of 2 (i.e., every third household) was employed in area sampling.
- Other measures taken to help achieve the target sample sizes:
- Expansion of barangays – if the required quota of 5 respondents per barangay was not achieved, the interviewer recruited from adjacent barangays
- Use of database – 2019 to 2020 respondents of previous surveys that used simple random sampling were utilized to reach the required sample size in specific cities.