Pollster.com: Michael McDonald on the CPS 2006 Turnout Data

June 29, 2007

Michael McDonald on the CPS 2006 Turnout Data

George Mason University Professor Michael McDonald, whose voter turnout web site is one of the most useful election data resources on the web, sends along this note:

The 2006 Current Population Survey (CPS) Voting and Registration Supplement, a primary source of data for many voting studies because of its large state sample sizes, is now available for download. To access these data, use the Census Bureau's Data Ferret program.

Preliminary analysis

The CPS reports that 47.8% (+/- 0.4%, remember, the CPS sample size of over 100,000 is very large and that margin of error varies with sub-sample sizes) of the citizen voting-age population reported voting, which compares to my most recent turnout rate estimate of 41.3%. The higher CPS turnout rate is consistent with a well-known phenomenon known as "over-report" bias, where more people report voting than aggregate statistics indicate. For comparison purposes, 46.1% of the 2002 CPS citizen voting-age population reported voting while my turnout rate estimate is 40.5%.

The overall percentage of the electorate reporting voting before Election Day is 18.5%, down slightly from 20.0% in 2004 and up from 14.2% in 2002. California and Washington saw an increases in early voting to 33.2% in 2006 from 29.9% in 2004 (CA) and to 71.8% in 2006 from 60.6% in 2004 (WA), however, increases were reported in only 15 states. This may reflect a tendency of early voting to drop off in midterm elections, so I would caution that 2006 is probably not indicative of a new downward trend in early voting which has increased strongly in every election since 1998 from 11.2%. (Of course, these are self-reported rates, not actual election statistics such as those collected by The Early Voting Center.) If these trends persist, it may very well be true that more Californians will have voted early before the 2008 New Hampshire primary than all New Hampshire voters.

Turnout by demographic categories show that higher turnout in 2006 versus 2002 likely came from younger, white, moderately educated citizens (slightly more women, too). Perhaps most interesting is the lower turnout among non-Hispanic African-Americans, which indicates that Democrats likely won in 2006 by expanding their base rather than relying on their core constituencies, though we can't know for certain from these data because the CPS does not ask who people voted for.

One other interesting tidbit is found in Tennessee where Harold Ford ran in a closely contested U.S. Senate race. If the CPS is correct, non-Hispanic African-American turnout rates went down in Tennessee a non-statistically significant amount between 2002 and 2006, from 41.1% to 38.9% (+/- 7.6%).