Estimating the US Presidential election result based on recent opinion poll levels

Opinion polls ahead of November’s presidential election contest in the United States of America have generally tended to be relatively favourable in recent weeks for Barack Obama with these polls putting him a few per cent ahead in head-to-head contests with his most likely opponents, Mitt Romney and Rick Santorum, and holding a significant poll lead over the other candidates for the Republican Party nomination. But it will not be the candidate who wins the most votes that wins this election (as proved to be the case in the controversial 2000 contest) but the candidate who wins the most Electoral College votes. Each of the states in the USA (and the District of Columbia) have a certain number of Electoral College votes attached to them, with this number based on the number of Senators (always two) and members of the House of Congress (a function of a state’s population level, but each state has at least one representative) representing the state. As such, the number of Electoral College votes assigned to different states is shaped somewhat by states’ population levels but with a bias towards the states with the smaller population levels as they will always be guaranteed three Electoral College votes

The proportion of Electoral College votes won by candidates in the presidential election does not measure up exactly to their actual share of the first preference vote. The disproportional nature of this electoral system is down to the fact that all the Electoral College votes on offer in a state are assigned to the candidate who wins the most votes in that state on a “winner takes all” basis. In some cases the level of difference/bias can be quite significant where winning candidates’ share of the Electoral College votes have been seen to far exceed their share of the popular vote in a number of past contests – ironically the 2000 contest was probably one of the most proportional contests in this regard. In order to assess how support levels evident in opinion polls might translate into Electoral College vote numbers, I attempt to estimate what the candidates’ first preference votes would be in the different states, assuming similar (proportional) change in party vote shares in all states along the lines of the constituency-level analysis of opinion polls model as covered in a number of posts on the politicalreform.ie website. How does this work? Well, for instance, on the basis of average trends across recent polls the Barack Obama vote in different states is now estimated to stand at 0.93 times the level of support he won in those states in 2008, while the Romney support levels is estimated to stand at 0.95 times the level of support John McCain won in those states in 2008.

This of course is a very rough model, and ignores the fact that changing support levels between elections tend to vary geographically, even within regions. In addition to this, the geography of support for the Republican and Democrat party candidates will in turn be dependent somewhat on the part of the USA that their different candidates hail from – running a presidential candidate from a certain region would probably see an increase the party’s share of the vote in that region.

Looking at recent opinion poll trends for a potential head-to-head contest between Barack Obama and Mitt Romney (based on the realclearpolitics.com website’s averaging out of recent opinion poll trends which currently estimates Obama to be leading Romney by 49.1% to 43.4%), the following would be my estimates as to the number of votes that would be won by the candidates in the different states (and the District of Columbia), the destination of Electoral College votes and the margin of victory for the winning candidate:

State Obama Romney Margin (%) Dem_EV Rep_EV
Alabama         755,528       1,205,377 -21.4% 0 9
Alaska         114,789         184,479 -21.4% 0 3
Arizona         960,996       1,170,702 -9.1% 0 11
Arkansas         392,225         607,204 -19.8% 0 6
California       7,685,012       4,769,734 21.5% 55 0
Colorado       1,196,833       1,021,777 7.3% 9 0
Connecticut         926,693         599,029 19.9% 7 0
Delaware         237,260         145,015 22.4% 3 0
D. C.         228,290           16,528 79.7% 3 0
Florida       3,977,298       3,850,804 1.5% 29 0
Georgia       1,712,751       1,949,813 -6.0% 0 16
Hawaii         302,656         114,743 41.4% 4 0
Idaho         219,596         383,548 -24.9% 0 4
Illinois       3,175,759       1,933,082 22.5% 20 0
Indiana       1,276,155       1,280,659 -0.2% 0 11
Iowa         769,888         649,423 7.8% 6 0
Kansas         478,094         665,865 -15.2% 0 6
Kentucky         698,415         997,826 -16.4% 0 8
Louisiana         727,210       1,092,818 -18.6% 0 8
Maine         391,866         281,013 15.2% 4 0
Maryland       1,513,386         913,505 22.8% 10 0
Massachusetts       1,768,453       1,055,301 23.1% 11 0
Michigan       2,667,941       1,949,699 14.3% 16 0
Minnesota       1,461,271       1,213,812 8.5% 10 0
Mississippi         515,149         689,602 -13.5% 0 6
Missouri       1,339,191       1,375,987 -1.3% 0 10
Montana         215,620         232,104 -3.3% 0 3
Nebraska         309,574         431,102 -15.2% 0 5
Nevada         495,713         392,889 10.6% 6 0
New Hampshire         357,412         301,247 7.9% 4 0
New Jersey       2,057,599       1,535,296 13.5% 14 0
New Mexico         438,767         330,082 13.1% 5 0
New York       4,462,648       2,619,824 24.1% 29 0
North Carolina       1,990,012       2,025,678 -0.8% 0 15
North Dakota         131,330         160,730 -9.3% 0 3
Ohio       2,730,600       2,548,493 3.2% 18 0
Oklahoma         466,699         913,793 -30.6% 0 7
Oregon         963,396         702,810 14.3% 7 0
Pennsylvania       3,042,960       2,527,617 8.6% 20 0
Rhode Island         275,444         157,403 25.0% 4 0
South Carolina         801,009         984,915 -9.6% 0 9
South Dakota         158,748         193,247 -9.0% 0 3
Tennessee       1,009,970       1,407,740 -15.3% 0 11
Texas       3,277,259       4,262,996 -12.2% 0 38
Utah         304,327         567,244 -27.5% 0 6
Vermont         203,642           94,194 33.7% 3 0
Virginia       1,819,938       1,641,695 4.8% 13 0
Washington       1,626,120       1,169,850 14.9% 12 0
West Virginia         282,211         378,270 -13.4% 0 5
Wisconsin       1,557,729       1,201,425 11.9% 10 0
Wyoming           76,965         156,991 -31.4% 0 3
Total  64,548,395  57,054,980 5.7% 332 206
        61.7% 38.3%

The degree of disproportionality associated with the Electoral College vote system is readily evident here – while Obama would be estimated to be 5.7% ahead of Romney based on the popular vote levels in recent opinion polls, the analysis suggest that this would translate into a 23.4% margin of victory for the Obama campaign in terms of the number of Electoral College votes won.

While this analysis suggests that Barack Obama would have a clear win in terms of Electoral College vote numbers (winning by around one hundred and twenty five Electoral College votes an inspection of the state level figures points to a number of narrow victories in the key swing states of Florida, Ohio and Virginia, which would narrow the Obama win down to just six Electoral college votes should these states fall to Romney instead.  In this case, attention would be pointed towards the “next most marginal” states which could ultimately prove to be the crucial battlegrounds in a close contest – Colarado, New Hampshire and Iowa, as well as Pennsylvania and Minnesota.

This can be seen if a situation in which there was practically a dead heat in terms of the share of the popular vote won by Obama and whoever the Republican candidate would be, with the two candidates each estimated to win 49.23% of the popular vote based on the share of the vote for Other candidates (1.54%) in the 2008 contest. It is interesting to noted that in this instance, Obama would be predicted to win the Electoral College vote by six votes on the basis of a more efficient geography of support with fewer votes being wasted in terms of big wins in his safe seats and narrow losses in the marginal seats as would be the case for the Republican candidate. However, these figures show that the presidency could be won or lost on the basis of a narrow swing to the Republican in one (or two)of the following key swing states – Colarado, Iowa, New Hampshire, Pennsylvania and Minnesota. (That said, a similar level of a swing from the Republican candidate to Obama  in Ohio and Virginia would see Obama take those states.) 

State Obama Republican Margin (%) Dem_EV Rep_EV
Alabama         757,594       1,367,416 -29.0% 0 9
Alaska         115,103         209,279 -28.9% 0 3
Arizona         963,624       1,328,079 -15.8% 0 11
Arkansas         393,298         688,830 -27.2% 0 6
California       7,706,024       5,410,927 16.9% 55 0
Colorado       1,200,105       1,159,134 1.7% 9 0
Connecticut         929,227         679,557 15.2% 7 0
Delaware         237,909         164,509 17.8% 3 0
D. C.         228,914           18,750 79.1% 3 0
Florida       3,988,172       4,368,466 -4.5% 0 29
Georgia       1,717,433       2,211,925 -12.6% 0 16
Hawaii         303,484         130,168 38.2% 4 0
Idaho         220,197         435,108 -32.6% 0 4
Illinois       3,184,442       2,192,945 17.9% 20 0
Indiana       1,279,644       1,452,817 -6.3% 0 11
Iowa         771,993         736,725 2.3% 6 0
Kansas         479,401         755,377 -22.3% 0 6
Kentucky         700,324       1,131,963 -23.6% 0 8
Louisiana         729,198       1,239,725 -26.0% 0 8
Maine         392,937         318,789 10.1% 4 0
Maryland       1,517,524       1,036,307 18.3% 10 0
Massachusetts       1,773,288       1,197,165 18.7% 11 0
Michigan       2,675,235       2,211,796 9.2% 16 0
Minnesota       1,465,266       1,376,985 3.0% 10 0
Mississippi         516,557         782,305 -20.6% 0 6
Missouri       1,342,853       1,560,961 -7.4% 0 10
Montana         216,210         263,305 -9.6% 0 3
Nebraska         310,420         489,055 -22.3% 0 5
Nevada         497,069         445,705 5.3% 6 0
New Hampshire         358,389         341,743 2.3% 4 0
New Jersey       2,063,224       1,741,685 8.3% 14 0
New Mexico         439,967         374,454 7.9% 5 0
New York       4,474,849       2,972,006 19.7% 29 0
North Carolina       1,995,453       2,297,989 -7.0% 0 15
North Dakota         131,689         182,337 -15.9% 0 3
Ohio       2,738,066       2,891,086 -2.7% 0 18
Oklahoma         467,975       1,036,634 -38.9% 0 7
Oregon         966,030         797,288 9.2% 7 0
Pennsylvania       3,051,280       2,867,404 3.1% 20 0
Rhode Island         276,197         178,563 20.7% 4 0
South Carolina         803,200       1,117,317 -16.4% 0 9
South Dakota         159,182         219,226 -15.7% 0 3
Tennessee       1,012,731       1,596,982 -22.5% 0 11
Texas       3,286,219       4,836,069 -19.2% 0 38
Utah         305,159         643,499 -35.3% 0 6
Vermont         204,199         106,856 29.9% 3 0
Virginia       1,824,914       1,862,387 -1.0% 0 13
Washington       1,630,566       1,327,113 9.9% 12 0
West Virginia         282,982         429,121 -20.4% 0 5
Wisconsin       1,561,988       1,362,932 6.7% 10 0
Wyoming           77,175         178,096 -39.6% 0 3
Total  64,724,868  64,724,868 0.0% 272 266
        50.6% 49.4%

As a point of contrast with the Romney analysis, carrying out a similar analysis based on a comparison of Obama and Santorum poll figures which currently estimate a Obama lead over Santorum by 49.7% to 43.3%  would suggest that Obama would win in a presidential election contest by a larger margin over Santorum in terms of his Electoral College vote tally, as he would also be predicted to win narrowly in Indiana based on these poll numbers in addition to the states he would be predicted to win in a contest with Romney as outlined above.

State Obama Santorum Margin (%) Dem_EV Rep_EV
Alabama         764,761       1,202,600 -20.9% 0 9
Alaska         116,192         184,054 -20.8% 0 3
Arizona         972,739       1,168,004 -8.5% 0 11
Arkansas         397,018         605,804 -19.2% 0 6
California       7,778,923       4,758,743 22.2% 55 0
Colorado       1,211,458       1,019,423 8.0% 9 0
Connecticut         938,017         597,649 20.7% 7 0
Delaware         240,160         144,681 23.1% 3 0
D. C.         231,079           16,490 80.7% 3 0
Florida       4,025,900       3,841,931 2.2% 29 0
Georgia       1,733,680       1,945,320 -5.4% 0 16
Hawaii         306,355         114,479 42.3% 4 0
Idaho         222,280         382,665 -24.4% 0 4
Illinois       3,214,567       1,928,628 23.3% 20 0
Indiana       1,291,749       1,277,708 0.5% 11 0
Iowa         779,296         647,927 8.5% 6 0
Kansas         483,936         664,330 -14.6% 0 6
Kentucky         706,949         995,527 -15.8% 0 8
Louisiana         736,097       1,090,300 -18.1% 0 8
Maine         396,654         280,365 15.9% 4 0
Maryland       1,531,880         911,400 23.6% 10 0
Massachusetts       1,790,063       1,052,870 23.9% 11 0
Michigan       2,700,543       1,945,206 15.1% 16 0
Minnesota       1,479,127       1,211,015 9.2% 10 0
Mississippi         521,444         688,013 -12.9% 0 6
Missouri       1,355,556       1,372,817 -0.6% 0 10
Montana         218,255         231,569 -2.7% 0 3
Nebraska         313,357         430,109 -14.6% 0 5
Nevada         501,771         391,984 11.3% 6 0
New Hampshire         361,779         300,553 8.6% 4 0
New Jersey       2,082,743       1,531,758 14.2% 14 0
New Mexico         444,129         329,321 13.8% 5 0
New York       4,517,181       2,613,788 24.9% 29 0
North Carolina       2,014,330       2,021,010 -0.2% 0 15
North Dakota         132,935         160,360 -8.6% 0 3
Ohio       2,763,968       2,542,621 3.9% 18 0
Oklahoma         472,402         911,688 -30.0% 0 7
Oregon         975,169         701,190 15.0% 7 0
Pennsylvania       3,080,145       2,521,793 9.3% 20 0
Rhode Island         278,810         157,041 25.8% 4 0
South Carolina         810,798         982,646 -8.9% 0 9
South Dakota         160,688         192,802 -8.4% 0 3
Tennessee       1,022,311       1,404,496 -14.7% 0 11
Texas       3,317,307       4,253,173 -11.6% 0 38
Utah         308,046         565,937 -26.9% 0 6
Vermont         206,131           93,977 34.5% 3 0
Virginia       1,842,178       1,637,912 5.5% 13 0
Washington       1,645,991       1,167,155 15.7% 12 0
West Virginia         285,659         377,399 -12.8% 0 5
Wisconsin       1,576,764       1,198,657 12.7% 10 0
Wyoming           77,905         156,630 -30.9% 0 3
Total  65,337,174  56,923,517 6.4% 343 195
        63.8% 36.2%

Again, the level of disproportionality associated with this electoral system is evident, with Obama estimated to win the Electoral College vote by a margin of 27.5% as against his much narrower lead over Santorum in the popular vote. Similar analyses based on poll figures for head to heads between Obama and Paul and between Obama and Gingrich suggest Electoral College vote wins for Obama by 368-170 over Paul and by 387-154 over Gingrich.

Advertisements

Tags: ,

4 Responses to “Estimating the US Presidential election result based on recent opinion poll levels”

  1. Dennis Pringle Says:

    Another factor to consider is who the successful Republican candidate selects as their running mate. Sarah Palin only delivered 3 electoral college votes last time from Alaska, but a running mate from a large marginal state could make a significant difference.

  2. Estimating the US Presidential election: applying national opinion poll levels to the state-level contests | Irish Elections: Geography, Facts and Analyses Says:

    […] The degree of disproportionality associated with the Electoral College vote system is somewhat evident here – while Obama would be estimated to be just 0.1% ahead of Romney based on the popular vote levels in recent national opinion polls, the analysis suggest that this would translate into a 1.2% margin of victory for the Obama campaign in terms of the number of Electoral College votes won. Such levels of disproportionality are likely to become more evident should the gap between the candidates widen during the course of the election, as evident in the 2008 result when Obama was ahead of McCain in the popular vote by 7.38% but was ahead of McCain by 35.72% in terms of the proportion of electoral college votes won by both candidates.  (And also look at the levels of the electoral college vote victories predicted for Obama on the basis of more favourable national polls some months ago, as detailed in an earlier version of this analysis on the Adrian Kavanagh commentary site.) […]

  3. US Presidential Election: Could Romney win the popular vote but lose the election? | Irish Elections: Geography, Facts and Analyses Says:

    […] The degree of disproportionality associated with the Electoral College vote system is somewhat evident here – while Obama would be estimated to be 1.5 percentage points behind Romney based on the popular vote levels in recent national opinion polls, the analysis suggest that this would translate into a 1.2% margin of victory for the Obama campaign in terms of the number of Electoral College votes won. Such a level of disproportionality may well become more evident should the gap between the candidates widen during the course of the election – as evident in the 2008 result when Obama was ahead of McCain in the popular vote by 7.38% but was ahead of McCain by 35.72% in terms of the proportion of electoral college votes won by both candidates. However a slight increase in Romney’s popular vote share would probably edge him into an electoral college vote lead and produce a more proportional result in this instance, as this would edge to victories in states such as Colarado, Iowa and New Hampshire where the above model has him narrowly losing out to Obama in. (Also look at the levels of the electoral college vote victories predicted for Obama on the basis of more favourable national polls some months ago, as detailed in an earlier version of this analysis on the Adrian Kavanagh commentary site.) […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: