Among the issues most commonly discussed are individuality, the rights of the individual, the limits of legitimate government, morality, history, economics, government policy, science, business, education, health care, energy, and man-made global warming evaluations. My posts are aimed at thinking, intelligent individuals, whose comments are very welcome.

"No matter how vast your knowledge or how modest, it is your own mind that has to acquire it." Ayn Rand

11 September 2012

Examining the 11 September Washington Post/ABC Poll

The Washington Post/ABC presidential poll of 11 September 2012 says that Obama leads Romney by 50% to 44% among registered voters and by 49% to 48% among likely voters.  This is not really the correct result of this poll.  In their poll, the respondents broke down by party affiliation as follows:

Democrats, 33%
Republican, 23%
Independent, 37%
Other, 4%
Don't Know, 3%

So the poll result among registered voters is that for which Democrat affiliation exceeds Republican affiliation by 10%!  According to a Rasmussen Report of polling in August 2012, the breakdown by party affiliation is actually:

Democrats, 33.3%
Republican, 37.6%
Other, 29.2%

The Republicans have a 4.3% advantage in party affiliation, not the 10% disadvantage of the WP/ABC poll.  Consequently, the poll claim that Obama leads Romney by 50% to 44% among registered voters is nonsense.  Let us assume that we can at least use the poll results for the percentage of Democrats, Republicans, and Independents who will vote for either Obama or Romney and recalculate the results with a proper weighting by party affiliation.  The poll says that:

Democrats will vote 91% for Obama and 5% for Romney.
Republicans will vote 6% for Obama and 89% for Romney.
Independents will vote 46% for Obama and 48% for Romney.

Now, I have a suspicion that just as the poll over-samples both Democrats and Independents, it also over-samples middle roader Republicans, given the higher vote percentage among Democrats for Obama than Romney gets among Republicans.  But, let us use these percentages anyway and combine them with the Rasmussen party affiliation results.  In addition, let us assume that among the Rasmussen others, about 4% are going to vote for the Libertarian, Green, Socialist Workers, or whatever other micro-party candidates are running.  I am taking the Independents to be 25.1% of the voters.  The registered voter result is then:

Obama:  (0.91)(33.3%) + (0.06)(37.6%) + (0.46)(25.1%) = 44.1%

Romney:   (0.05)(33.3%) + (0.89)(37.6%) + (0.48)(25.1%) = 47.2%

Thus by declared party affiliation, Romney leads Obama by 47.2% to 44.1%.  This is a Romney advantage of 3.1%.  When the WP/ABC poll made likely voter corrections, the big change was due to their assumption that Romney's advantage among Independent voters would increase from 2% to 11%.  Applying their expected likely voter percentages to the party affiliation percentages of Rasmussen, one gets the likely voter result:

Obama:    (0.94)(33.3%) + (0.06)(37.6%) + (0.43)(25.1%) = 44.4%

Romney:   (0.05)(33.3%) + (0.91)(37.6%) + (0.54)(25.1%) = 49.4%

So the likely voter advantage for Romney over Obama is 5.0%!  Now, I am not highly confident in the adjustments the WP/ABC poll makes for likely voters, but the Romney advantage in registered voter results of 3.1% will likely grow at the polls due to the likely higher turn-out of Republicans and those Independents favoring Romney.

Of course, if Romney does win the popular vote by 5%, it is extremely unlikely that he will not also win the electoral vote.


Harry Dale Huffman said...

Good. This deserves media-wide coverage. I shared it on twitter (the first time I have done that).

Charles R. Anderson, Ph.D. said...

Thank you Harry.

Editor said...

Great Job! Please's my 2 cents...

Obama leads by 2%
DEM 33%
REP 28%
IND 34%

"Obviously, if Romney is leading among independents by four, yet trailing overall by two points, both polls have probably sampled more Democrats. Indeed, the WaPo poll is D+5.

This is a big improvement over past WaPo polls, which assumed that Democrats would have a bigger turnout than 2008's D+7 electorate.

I think today's poll is still overly generous to Democrats, but it is more realistic than their previous polls.

Washington Post/ABC OLD POLL: Sept. 11th
Obama leads by 6%.
DEM 33%
REP 23%
IND 37%

RASMUSSEN: Party ID (Aug 20th)
* How does a poll (above) have a 10% advantage of Dem vs Rep...but there are more republicans?
Democrats, 33.3%
Republican, 37.6%
Other, 29.2%

Charles R. Anderson, Ph.D. said...

Hi Editor:

I just put up a post making the same party affiliation adjustment of results on the latest Washington Post/ABC News poll at

Romney as a 2.8% advantage among registered voters and a 4.6% advantage among likely voters using the likely voter weighting used in this poll. It seems strange to me that this poll implies and even split of Independent registered voters. We shall have to see if that remains the case in future polls.