Unit

Sampling, variance, analysis, reporting, and dissemination units cover most of the unit types of interest in survey methodology. Sampling units can be primary, secondary, tertiary, and beyond—also known as first-stage, second-stage, and so on. These refer to a hierarchy of smaller and smaller geographic or organizational structures that have been exploited in the sample design to improve efficiency. In face-to-face surveys of the general population, the stages are [Page 925]typically county (or count group), block (or cluster of neighboring blocks), housing unit (or other quarters), and person. In student surveys, the stages are typically school district, school, classroom, and student. In random-digit dialing surveys, the stages are typically just household and person, although sometimes a 100-bank is also a stage.

Variance units are often the same ...