In the Understanding America Study (UAS), sample weights are survey-specific. They are provided with each completed UAS survey and, unless otherwise specified, are meant to make each survey data set representative of the U.S. population aged 18 and older with respect to a pre-defined set of socio-demographic variables. Sample weights are constructed in two steps. The first step concerns the computation of base weights, which correct for unequal probabilities of sampling UAS members. In a second step, final post-stratification weights are generated, allowing the sample of each study to align with the reference population along certain socio-demographic dimensions.

Sample weights are constructed only for the nationally representative core sample. UAS members belonging to the special purpose samples of Native Americans and Los Angeles County residents have zero base weight and zero final post-stratification weight.

Detailed information about the UAS weighting procedures can be found in the UAS Weighting Procedures. For questions about these procedures or if a weighted data set is not yet available for a survey, please email

Note: Per September 1, 2017 the UAS weighting procedures have been updated. For a description of the previous procedures please click here. Data sets with weights based on the earlier procedures are available on request by email at