The 2010 Civic Health Index is based on The Center for Information & Research on Civic Learning and Engagement's (CIRCLE) analysis of Census Current Population Survey (CPS) data. Volunteering estimates are from CPS September Volunteering Supplement, 2007, 2008 and 2009, and data available from Volunteering in America. Voting and registration data come from the CPS November Voting/Registration Supplement, 2004 and 2008, and all other civic engagement indicators, such as access to information and connection to others, come from the 2008 and 2009 CPS Civic Engagement Supplement. For these indicators, the 2008 and 2009 data were combined whenever possible, to achieve the largest possible sample size and to minimize error.

For the Illinois Report, the sample size for citizen engagement was 6,037 and the sample size for volunteering 3,164. Because the report draws from multiple data sources with varying error parameters, there is no exact estimate of margin of error for the national or Illinois sample. However, according to the Census Bureau, published margin of error for CPS voting and registration supplement from 2008 is +/–0.3% for the national estimate and +/– 1.5% for Illinois. i For specic population subgroups, the margin of error is greater.

The 2010 national report, America's Civic Health Assessment issue brief and executive summary can be found online at www.ncoc.net/Civic Health2010. Rankings and data for all 50 states and 51 largest metropolitan areas are available at http://civic.serve.gov. A chronicle of Illinois Civic Health Index work since 2009 can be found at NCoC.net/IL.