Their estimates rely on a key question from the Cooperative Congressional Election Study: “Are you registered to vote?” Notably, this is not the same question as “Are you registered to vote in the United States?” In principle, non-citizens could be registered to vote only in their home country and respond affirmatively, and truthfully, to the question on the survey.
(Respondents are asked for the Zip code at which they are registered to vote, but this could be interpreted as the Zip code at which non-citizens receive absentee ballots from abroad. Mexico, for example, has allowed absentee voting by mail from abroad since 2005.) If this sounds outlandish, consider that 20 percent (15 out of 75) of those non-citizens claiming to be registered in 2008 were in fact verified as not being registered to vote in the United States. Another 61 percent (46 of 75) could not be matched to either a commercial or voter database. That leaves only 14 out of 75 non-citizen respondents claiming to be registered in 2008 who were in fact confirmed as registered to vote in the United States.
This raises a more general point: The Cooperative Congressional Election Study, which focuses on the behavior of citizens, is ill-suited to examine the behavior of non-citizens, who make up about one percent of the sample. One consequence of this is that the number of respondents who report that they are not citizens yet vote or are registered to vote is quite small in absolute terms: in 2010, for example, only 13 respondents — not 13 percent, but 13 out of 55,400 respondents — reported that they were not citizens, yet had voted. Given the ever-present possibility of respondent or coder error, it takes a bit of hubris to draw strong conclusions about the behavior of non-citizens from such small numbers.
Update from a reader:
In your follow-up to the post about non-U.S. citizens electing Al Franken, it maybe worth noting:
1. The authors of the original study say a follow-up will be posted at the Washington Post any day responding to critics.
2. I investigated the study, specifically looking at the question of whether the public should be worried that Democrats will win tight 2014 elections because of noncitizen voters. On a scale of 0 to 10, with 10 being absolutely true, 0 being wildly false and 5 being half-true, I rated this claim a 4, meaning slightly false. Study author Jesse Richman responded that he agreed.
He said two things your voters may be especially interested in that are a bit of a walk-back from his original post: “Noncitizen voting might tip one or two extremely close races but is unlikely to tip the balance in the Senate, and certainly not in the House.” And: “More work is needed. We view our study as the beginning of the process, not the definitive work on the question.” You can read his full email reply here.