Roper Center ArchivesThe Center’s mission is to collect, preserve, and disseminate public opinion data; to serve as a resource to help improve the practice of survey research; and to broaden the understanding of public opinion through the use of survey data in the United States and abroad. Most of the surveys in the Roper Center were conducted on national samples, but there are also some state and local surveys, as well as a number of surveys of special populations of interest. Nearly all of the surveys are based on representative samples drawn according to the best practices of the time.