Statistical Web Sites
The Association of Religion Data Archives (ARDA) strives to democratize access to the best data on religion. Founded as the American Religion Data Archive in 1997 and going online in 1998, the initial archive was targeted at researchers interested in American religion. The targeted audience and the data collection have both greatly expanded since 1998, now including American and international collections and developing features for educators, journalists, religious congregations, and researchers. Data included in the ARDA are submitted by the foremost religion scholars and research centers in the world.
When using ARDA data in publications and presentations, the author should acknowledge the Association of Religion Data Archives and the original collector(s) of the data (e.g., The data were downloaded from the Association of Religion Data Archives, www.theARDA.com, and were collected by [name of principal investigator(s)]).
—About the ARDA, retrieved June 26, 2015.
"Hartford Seminary's Hartford Institute for Religion Research has a thirty-five year record of rigorous, policy-relevant research, anticipation of emerging issues and commitment to the creative dissemination of learning. This record has earned the Institute an international reputation as an important bridge between the scholarly community and the practice of faith. Statistical data is used in many of its studies.
—Who We Are, retrieved July 7, 2013.
A useful website, but data is not always up-to-date or carefully documented. Make sure you can otherwise verify its contents.