Secondary data is data that a researcher has not collected or created themselves. Secondary data can encompass an enormous range of highly original and extensive studies, including some of the largest and most careful collections of data. This guide is a very quick introduction to locating secondary data sources.
We will review the following strategies for locating data: Search, Citation, Databases and Archives, and Producers.
There is nothing wrong with searching Google or other search engines (Bing, anyone?) for relevant data, just by trying some keywords (e.g., "incarceration rates in the US"). This will often surface some of the major sources of data, sometimes in the form of a press release. It is important to dig further into the sources you find in order to look for complete, downloadable datasets.
There are an increasing number of search sites that offer up data directly, such as Data.gov (for open data released by US governmental agencies, sometimes in very raw form) and Datacite.org (providing a basic index to dataset that have received a Digital Object Identifier, often scholarly in nature). These sites can sometimes producing an overwhelming number of hits on a general topic, so refine your search!
Being familiar with the literature in your discipline can be an important step on the path to finding the perfect dataset. Look for the papers in your subfield that deal with your topic. What data sources are they using? Are they working with general-purpose datasets, or do the researchers have to collect their own data or do mashups of other sources? This will give you an idea of the possibilities and limitations of data on your topic. Also, knowing the exact name of a specific source (or even better, the DOI) can make it much easier to locate. Disciplinary indexes like Social Services Abstracts and Econlit are examples of places to look for these articles. You can find many more on the Libraries' list of indexes.
3. Databases and Archives
There are many specialized databases and archives that focus on providing data. Data-Planet Statistical Datasets provides one consistent interface to look up statistics on many topics, and data series are available for download. The focus is on selected time-series data, rather than panel or microdata.
ICPSR (the InterUniversity Consortium for Political and Social Research) is the largest social science data archive in the world, and contains a rich variety of complete datasets on a range of topics. Datasets are sourced from many places, from large federal and international organizations, states, nonprofits, and individual researchers. The datasets that ICPSR provides are well-curated, with full codebooks and typically available in multiple statistical software formats. This is a "must" for the researcher. ICPSR has many video tutorials and guides to using their collection on their Help Page.
Other databases such as the Roper's Centers iPoll Databank focus on surveys, but also have complete datasets available for download. Outside of the US there are many national level data archives. One place to find some of these in Europe is by browsing the CESSDA membership. CESSDA is the Consortium of European Social Science Data Archives.
For archives on other countries and topics, please ask your Data Librarian! (my contact info in the box at right --->)
4. Producers, i.e. Direct from the Source
Often you will learn through your research of the primary producers of data. In the US, government agencies such as the Bureau of the Census, the Bureau of Labor Statistics, the Centers for Disease Control and Prevention, the National Center for Education Statistics, and many more distribute data directly. While their web portals may focus on quick lookups of data, or statistical summaries, with a little bit of digging, you can find the places to download complete datasets or customized extracts of data. These tools vary for each source.
For international data, you can get large scale comparisons from the data portals of the United Nations or the World Bank. Or you can seek out country-level information from the relevant agencies, such as the National Statistics Office of Mongolia. The United Nations Statistics Division maintains a listing of national statistical offices that may be useful in this context.
Regardless of the topic, getting familiar with the producers of data on the topic will greatly benefit your research in the long run.
And for any other data-related questions you may have, please ask your Data Librarian! (my contact info in the box at right --->)
Rutgers, The State University of New Jersey, an equal access/equal opportunity institution. Individuals with disabilities are encouraged to direct suggestions, comments, or complaints concerning any accessibility issues with Rutgers web sites to: firstname.lastname@example.org or complete the Report Accessibility Barrier / Provide Feedback Form.