Respuesta :
National samples usually include about 10,000 people
Many studies rely on households as the primary unit of sample selection. However, household sampling frames are not widely available and can be expensive to manufacture. Household addresses obtained from US Postal Service (USPS) information are not yet a representative list of US households, as certain types of households are undervalued. To provide sampling frames for many surveys, the University of Chicago's NORC has created household sampling frames that represent more than 99% of US households.
2010 National Frame selected a representative sample of US households using a two-level probabilistic sampling design. In the first phase, the sampling unit is the National Frame Area (NFA) defined using the 2010 Census Area, and each NFA contains at least 10,000 inhabitants.
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