All persons aged 15 years and over are covered, excluding institutionalized persons, foreign citizens on short-term stay, and persons residing abroad. The survey is quarterly, with interviews conducted continuously through the quarter. Selected dwellings remain in the survey for five consecutive quarters. Fieldwork is undertaken continuously throughout the year. A permanent survey organization conducts the survey.
Interviewers are staff of regional statistical offices.
The total nonresponse rate is 6 percent.