Illinois 2010 Senate True Vote Analysis
June 18, 2011
This is an analysis of the 2010 Illinois senate race in which Kirk (Rep) defeated Giannoulias (Dem) by 60,000 recorded votes (49.2-47.6%).
Giannoulias won the unadjusted exit poll by 51-47%, a 144,000 vote margin.
The True Vote Model indicates that he won by 49.7-47.1%, a 97,000 margin.
The Final Illinois 2010 Exit Poll indicated that 56% of the votes recorded were cast by returning Obama voters and 38% by returning McCain voters.
The 2008 Presidential True Vote analysis indicates that Obama won nationally by 58-40% – a 22 million vote margin (only 9.5 million was recorded). Forcing the State and National Exit Polls to match the recorded vote is standard operating procedure. In order to force a match in 2004 and 2008, the exit pollsters had to assume an impossible number of returning Bush voters from the previous election. The Final Exit Poll is forced to match the recorded vote by adjusting the returning voter mix and/or the vote shares. In 2004, the impossible Bush 2000 voter 43% share of the mix was insufficient to match the recorded vote; the exit pollsters also had to increase Bush vote shares.
The returning voter mix should reflect the previous election True Vote, not the recorded vote.
Assume a) 61% turnout of Obama voters, b) 69% McCain turnout and c) an even spit between Gianoulias and Kirk among new and returning third-party voters. The True Vote Model indicates that if Giannoulias captured just 82% of returning Obama voters, he won by approximately 115,000 votes. With an 80% share of returning Obama voters, he won by 33,000 votes.
As in the Wisconsin and Pennsylvania senate exit polls, vote shares were not available for returning third party (Other) voters and new (DNV) voters. However, the Illinois exit poll indicated that returning 2008 third-party voters and new voters each comprised 3% (108,000) of the vote. There were only 72,000 third-party voters in 2008. Approximately 48,000 returned to vote in 2010. Therefore, the returning third-party mix was changed to 1.3%. The DNV increased from to 4.1%.
The sensitivity analysis tables display Giannoulias’ vote share and margin for various scenarios: 1) Obama 2008 voter turnout in 2010 (61-69%), 2) Giannoulias’ shares of returning Obama voters and 3) Kirk shares of returning McCain voters.
Exit Poll Oddities
The Final 2010 Illinois Exit Poll is eerily similar to the Wisconsin amd Pennsylvania polls. Apparently, the exit pollsters forgot to adjust “When Decided” to match the recorded vote in each election. Feingold in Wisconsin, Sestak in Pennsylvanua and Giannoulias in Illinois each won the “When Decided” category in the Final. But they lost in the other categories.
Giannoulias had a 54-37% lead among the 29% of voters who decided in the month before the election. He won the “When Decided” category by 49.4-46.1%.
The Democrats led in Party ID by 44-31% over the Republicans. Democrats virtually always win when they have an edge in Party-ID. Kirk needed an implausible 61% of Independents.
Giannoulias tied Kirk among the 94% who were returning Obama and McCain voters in the “How Voted in 2008” category,
At the same time, to believe the Illinois recorded vote, you must also believe that one out of five returning Obama voters defected to Kirk but only 1 out of 33 returning McCain voters defected to Giannoulias.
You must also believe that just 61% of Obama voters returned to vote while 70% of McCain voters did.