In this category, a number of comprehensive microdata sources are listed and annotated. These comprehensive sources contain a variety of different data sets on a variety of topics. If you are not certain about what kind of microdata you are looking for, or you are not sure about the data availability, or you just want to get a general sense of what microdata is like, then this category would be a good starting point.
The Inter-University Consortium for Political and Social Research (ICPSR), established in 1962, is an integral part of the infrastructure of social science research, with perhaps the richest collection of microdata files among all the data archives. A unit within the Institute for Social Research at the University of Michigan, ICPSR is a membership-based organization, with over 400 member colleges and universities around the world. ICPSR maintains and provides access to a vast archive of social science data for research and instruction, offers training in quantitative methods to facilitate effective data use, and provides user support to assist researchers in identifying relevant data for analysis and in conducting their research projects.
The UK Data Archive at the University of Essex houses the largest collection of accessible computer-readable data in the social sciences and humanities in the United Kingdom. It is funded by the Economic and Social Research Council (ESRC), the Joint Information Systems Committee (JISC) of the Higher Education Funding Councils and the University of Essex. Founded in 1967, it houses several thousand datasets of interest to researchers in all sectors and from many different disciplines. It also houses the History Data Service, part of the Arts and Humanities Data Service funded by the Arts and Humanities Research Council (AHRC) and JISC. To use the services, first, users must register. Registration is a simple, online procedure which only needs to be done once. Once registered, users are then free to order data online in a variety of formats and media, or, for most popular datasets, access them online via the NESSTAR system. For some users, there may be administrative fees, but for the vast majority of users, the only cost is the price of the medium (CD or disk) and postage/packing.
The Social Science Data Archives (SSDA), located in the Research School of Social Sciences at the Australian National University, was established in 1981. Its missions are to collect and preserve computer-readable data relating to social, political and economic affairs and to make the data available for further analysis. In addition to its acquisition and distribution activities, the Social Science Data Archives has established a library of reference sources to data collection activities in Australia, including the data collection activities of Commonwealth and State government agencies, major polling organizations and individual researchers of Australia.
The Odum Institute, located at the University of North Carolina - Chapel Hill (UNC), maintains one of the oldest and largest comprehensive archives of machine-readable statistical data in the U.S. Its Louis Harris Data Center is the exclusive national repository for Louis Harris public opinion data. The Data Library of IRSS holds an extensive collection of U.S. Census data, a variety of public opinion, economic, health, and education data. It is the only archive of the raw data from the Computer-Administered Panel Study (CAPS) which collected personality and social psychological microdata from annual samples of UNC undergraduates from 1983 to 1988. The strengths of its collection are in public opinion microdata data and North Carolina state data.
DPLS at the University of Wisconsin - Madison is the central repository of data collections used by the social science research community at the University of Wisconsin-Madison. DPLS acquires, preserves and facilitates access to social science data resources, provides reference and technical services to researchers, and assists in the archiving of locally produced data. While the topical coverage of its data collections is comprehensive, DPLS holds a very strong collection of longitudinal data files which are all microdata.
CESSDA (Council of European Social Science Data Archives), maintains links to all of the major data archives or data libraries. From these links, you may explore more microdata sources in North America, Europe, Africa, Latin America, Middle East, Asian and Pacific area, where you can find relevant regional and local microdata resources.