The American National Election Studies' Guide provides immediate access to tables and graphs that display the ebb and flow of public opinion, electoral behavior, and choice in American politics over time.
ICPSR maintains a data archive of more than 500,000 files of research in the social sciences. It hosts 16 specialized collections of data in education, aging, criminal justice, substance abuse, terrorism, and other fields.
Understanding the Raw Data
In order to understand, interpret, and analyze raw data sets, you need to find the data set's:
Summary or Description of the data set
Codebook (or at least the original survey/questionaire)
Data Set (try to download it as a Deliminated .txt or .csv file so you can import it into MS Excel)