NORC designs and maintains a multistage sample of geographical areas and a corresponding frame of housing unit addresses for national area probability studies, particularly for the General Social Survey (GSS). With each re-design of this frame, we incorporate innovations such as the Ernst procedure for maximizing the overlap of PSUs and new methods for compiling high quality address lists. In fact, NORC is one of the pioneers in the use of the USPS address list and geographical information systems for sample design and selection. Sampling staff members also use census datasets and special source materials such as directories, lists, and commercial databases to select many types of samples, including special subpopulations and business establishments. For telephone surveys, NORC can generate national, regional, or local samples. NORC staff have expertise in adaptive sampling techniques and audit sampling, as well.
NORC has extensive experience designing and conducting epidemiological studies, site-based studies, list studies, area probability studies, panel studies, longitudinal studies, and cross-sectional studies.