Understanding Political Polls: Is the GOP Underweighted?


Republicans, especially president Trump complain Republicans are undersampled in political polls.

Trump Demands CNN Apologize for a Poll Showing Biden in the Lead

On June 10, I noted Trump Demands CNN Apologize for a Poll Showing Biden in the Lead

Trump Hires Own Pollster

For months I have been reading the same thing: There is bias in the polls, many say on purpose.

Are the Polls Missing Republican Voters?

Nate Cohn asks and answers Are the Polls Missing Republican Voters?

There are many reasons the polls might ultimately be wrong in November, as many state polls were four years ago, but there’s no serious evidence that the polls are systematically missing Republican voters. There’s more evidence to the contrary — that the polls represent Republicans just fine, and President Trump still trails.

We know that registered Democrats outnumber registered Republicans in Florida by a few points, even if we don’t know whether those same voters would identify as Democrats or Republicans today.

Pollsters can take advantage of this if they use voter registration files, a large data set of every registered voter. Most private pollsters and a handful of high-quality public ones use voter registration files as the foundation of their polling, and these pollsters can use a respondent’s party registration to help ensure that their sample is representative. They can make sure that 37 percent of their respondents in Florida, for instance, are registered Democrats. In states where voters do not have the opportunity to register with a party, a pollster can use a voter’s primary participation history in a similar way.

Surprisingly, registered Republicans were actually more likely than registered Democrats to respond to the Times/Siena survey. This seemingly noteworthy difference can be explained by well-known demographic biases in polling: Older, rural and white voters are likelier than young, urban and nonwhite voters to respond to surveys. After these factors were controlled for, Republicans were no likelier than Democrats to respond to the survey.

Mr. Trump’s problem wasn’t the number of people who said they voted for him last time: It was that only 86 percent of those who said they voted for him last time said they would do so again. 

Why Don’t Polls Include the Same Number of Republicans and Democrats?

Nate Cohn provided one look above, here is another from Pew Research.

Newcomers to polling sometimes assume that if you are asking Americans questions about politics, it’s only fair to include an equal number of Republicans and Democrats. While this notion makes some sense on the surface, it’s based on a misunderstanding of what polling is intended to do. The goal of a national political survey isn’t to artificially even the playing field. It’s to represent groups in their actual proportions within the country. And a wide range of evidence shows that there are more Democrats than Republicans in the United States today.

In the 31 states that register voters by party, the number of Americans registered as Democrats outnumbered those registered as Republicans by nearly 12 million in mid-2018. Registration with a party is an imperfect measure of whether a person currently identifies with that party, especially in the South. But nationwide comparisons find that registration is closely associated with self-identification, and the two appear to be growing more correlated over time.

In addition, commercial voter files – which attempt to predict the partisanship of voters in all 50 states and the District of Columbia based on information such as address, race, age and primary vote history – indicate that there are more Democratic registered voters than Republican registered voters in the country today.

So what does all this mean for consumers of political polling? In general, poll watchers today should expect to see more Democrats than Republicans in a national survey, particularly one designed to reflect the views of U.S. adults (as opposed to registered or “likely” voters). These partisan breakdowns don’t necessarily favor one side or the other; rather, they reflect the population in question as accurately as possible.

Getting it Totally, Yet Typically Wrong

There are hundreds more similar Tweets.

Reweighting Polls

The subject of weighting came up today in a Twitter Thread by Nate Cohn.

  1. You can't just reweight a poll by changing the proportions in the crosstabs, since that can throw off other variables. You've got to weight on everything at once.
  2. As an example, many noticed our AZ poll had like Trump>10 on '16 recalled vote. But you can't just unskew it 5 points to the left. Our poll, as it was, had the right number of reg Ds/Rs; unskewing on the '16 vote tab would have meant giving Dems a reg advantage in AZ
  3. If you just give more weight to the GOP in the sample, you just made your sample whiter than it should be, or maybe now you have too few young voters, or too few people outside the South, and so on.

Finally, there are initial polls and weighted polls. It is not impossible to get the correct number of respondents by age, sex, education, and political affiliations.

That is why pollsters release weighted and unweighted responses. 

Pollsters Not Purposely Biased

The independent pollsters try to get it right, including those for Fox News, rated A- by Nate Silver at FiveThirtyEight. By contrast McLaughlin is rated C/D.

Beware of party sponsored polls which have one purpose only. They are not unbiased.

Were the Polls Wrong in 2016?

They were not great but almost all of the were within margins of error.

The Midwest state polls did make one mistake in regards to education. Poll samples likely overweighted educated voters.

The turnout had a large number of white voters without a college degree. Trump appealed to those voters and won enough of them to flip key states.

Comey Factor

Trump had a huge surge at the last moment due to a blockbuster announcement by FBI director James Comey.

FiveThirtyEight comments The Comey Letter Probably Cost Clinton The Election , So why won’t the media admit as much?

Trump won Michigan, Pennsylvania, and Wisconsin by less than 1 percentage point. 

The Comey effect was not reflected in the polls at the state level but it swung the election.

Had Trump not won those states, we would not have all this bickering today about the polls being wrong.

Trump is on the Short End of the Enthusiasm Gap

Another misconception is that Trump supporters are more enthusiastic than Biden supporters. 

On the surface, that is true, but only if one looks at positive enthusiasm. 

Voters Dislike Trump More than Biden

If you take negative enthusiasm into account Trump is on the Short End of the Enthusiasm Gap.

Biden Hold a Net Enthusiam Advantage

Not a 2016 Replay

For many months, I have commented this is not a replay of 2016. Trump was never well liked, but many people in both parties despised Hillary.

Trump won in 2016 for five reasons.

  1. People hated Hillary more than Trump
  2. Trump was an unknown risk that swing voters were willing to take a chance on
  3. Hillary ran a very poor campaign
  4. A fantastic campaign slogan: Make America Great Again
  5. At the last minute, Comey rescued trump with an attack on Hillary and her email server.

Points 1-4 got Trump into the ballpark. It still took Point 5 to cross the finish line.

Despite all of those things Trump barely won as measured by tiny margins of victory in several critical swing states.

The Man People Hate to Hate

Biden is a man people hate to hate. Trump and Hillary are candidates people love to hate.

There is no enthusiasm gap for Trump, except in the negative sense. 

Many people despised Hillary, and rightfully so. 

The election is now less than three months away. It is not "early" but nor is it "too late".

Trump could still win but it is an extremely uphill battle at this points. Polls will likely narrow, just not by enough.


Comments (31)
No. 1-14

It doesn't make sense for pollsters to ensure they have the right mix of republicans, democrats, and independents. If they just sample randomly the right mix will automatically be created, within a margin of error, the same way the math of the poll is supposed to be working.



If you end up with the right weighted mix, you have a decent poll.
Last-minute politics by Comey were not reflected in the polls. And the education mix was off.

Bungalow Bill
Bungalow Bill

"His favorability is higher than 42%. Look at his ground support and the size of his rallies. With over 90% negative coverage, the polling has to fit the narrative. These polls are underweight Republicans, in other words they dont represent the RL proportion of registered voters"

Funny tweet! I remember people calling into conservative talk radio shows in 2012 telling us they just knew the polls were lying about Mitt Romney because the yard signs in peoples yards in their communities all were for Romney. The yard sign caucus...


The Disconnect Between the Stock Market and the Real Economy Is Destroying Our Lives
Stocks are the wall that protects the rich from the consequences of this crisis http://inthesetimes.com/article/22504/stock-market-real-economy-disconnect-unemployment-poverty-coronavirus-trump


The one thing that is not mentioned is the GOP is shrinking in terms of registrations with the party. More people are leaving both parties but the GOP is losing people faster. This might be why the polls say the GOP is underweighted. But they deserve to be whatever the population identifies as. Right now my guess is 45% identify as Dem. 35% identify as Republican. 20% identify as indepedent. The GOP would have to win 75% of the indepedent vote in swing states for Trump to stay in office. They will be lucky not to lose the Senate. The bottom line here is a Republican president presides over the start an economic disaster every time this century. Bush 2001-2002. Bush 2007-2008. Trump 2020. Incumbent Republicans are going to PUNISHED by voters.

Tony Bennett
Tony Bennett

"Trump could still win but it is an extremely uphill battle at this points. Polls will likely narrow, just not by enough."


I'm not ready to bury DJT yet. And I don't think Comey in 2016 played that big of a role. Of course, all the talking head "experts" blamed it on Comey. The same "experts" who were dead wrong pre election. Why should I take their word ... on ANYTHING?

From about 2 months prior to election in 2016 I would often watch both campaign's rallies on C-SPAN. The differences couldn't have been starker. HRC (or Kaine) surrounded on dais by all the local / state leaders. Crowds were undersized with golf clap enthusiasm. DJT was a pariah even then. Local / state Republicans stayed away from his rallies in droves. Often his rallies were on the airport tarmac ... with no one to introduce him. Yet the rallies were overflowing and rock concertish. I would watch and think this is going to be a lot closer than they think.

I just don't see Biden moving the needle ... a lot will turn on what happens in October.


Still using the New York Times as an unbiased source of information?

Nate Cohn at best remembers only 3 Presidents, Clinton left office when Nate was 13.

Experts can debate endlessly about how to make a poll accurate, just as there is endless debate why the stock market goes up or down... It's simple " are there more people buying or selling"


Mish, what about your platform here as a proxy? When I started posting here there were considerable trumpers defending trump, now there is hardly a post defending trumps actions. It is a bit ironic because trump needs support now more than ever.

If you had the right tools, you could run a query against all the comments posted and figure out the ratio of for/against comments over time.


Seems to me that enthusiasm, or lack thereof, is going to be a huge factor in this election. It doesn't matter if a person leans red/blue when they're insufficiently motivated to head to the polls.

It's hard to imagine anyone being pumped up about either of these candidates. Trump's 2016 outsider cred is long gone and Biden is a consummate insider. People seem to think that dislike of the other candidate is all a voter needs, but that's a cynical and unnatural mindset. People generally want to like something, not just dislike everything else. Nobody walks into a restaurant and orders something simply because they don't completely hate it.

I could easily see people saying they lean toward one or the other but end up being disgusted enough to stay home in November. I'll be very curious to see the final turnout numbers.


Republicans were not undercounted in 2016, the undereducated were. That was a key finding when the dust from 2016 settled. The pollsters have addressed this. The second error was not by pollsters but by analysts looking at the poll when they failed to account for the large number of undecideds. This is not the case today.

I find the logic that because 2016 didn't turn out as expected we should therefore ignore polls flawed. The correct answer is to correct the methodologies. This was done. If Trump really believed polls were irrelevant he wouldn't use them. He does.

At least three key types of error have emerged as likely contributors to the pro-Clinton bias in pre-election surveys. Undecided voters broke for Mr. Trump in the final days of the race, or in the voting booth. Turnout among Mr. Trump’s supporters was somewhat higher than expected. And state polls, in particular, understated Mr. Trump’s support in the decisive Rust Belt region, in part because those surveys did not adjust for the educational composition of the electorate — a key to the 2016 race.


Stocking up on coloring books, aroma therapies, and support gerbils for all my TDS friends. Meanwhile it will be open season on nearly all incumbents from BOTH useless parties and their truly bilateral SWAMP.


A few other events that happen in 2016 that tipped the scales to Trump:

  1. Hillary Clinton falls near the 9/11 memorial. I don't think this event pushed some independents into leaning Trump.
  2. GRU and Wikileaks hack DNC/Podesta emails that drop the same weekend as the Trump "grab em by the pussy" video/audio. This changes the narrative very quickly and most people forget about Trump and focus on DNC and Podesta email details.
  3. Too many assumed the polls were right and didn't go to vote.
  4. A weak economic recovery in the midwest tipped the scales away from the incumb ent who in this case was Clinton.

I voted for Trump in 2016 because he supported policies I like. Now, I realize it was Bannon talking through Trump. The tax cut for the rich he pushed through turned me against him. How in the world do we deserve two old fogies to choose from?


The Polls are making these numbers up. The past tells us this is true, They are manipulating peoples opinions. It could be considered felony for nondisclosure.