Many statistical packages require specific formats for data input and will produce only a limited set of output formats. Please check the help files for the software you are using to ensure that you will be able to get data in the format you need.
Statistical data sources - MHC digital collections
Social science data sets are available for downloading; coverage includes but is not limited to the U.S. Census, crime and criminal justice, foreign and national opinion polls, health, consumer studies, and historical data sets.
"The home of the U.S. Government's open data." Includes data sets from Federal and State agencies as well as other organizations. Topic categories include agriculture, business, climate, consumer, ecosystems, education, energy, finance, health, local government, manufacturing, ocean, public safety, science & research. File formats vary for different data sets, but among those available may be Excel, CSV, txt(csv), xls.