2020 Iowa Caucuses: How did my polling averages fare?

Given the extremely volatile polling for the 2020 Democratic presidential nomination following the conclusion of the Iowa Caucuses, I will not provide global monthly updates for next few months. Instead, I will focus on the first handful of primaries and caucuses: Iowa on February 3, New Hampshire on February 11, Nevada on February 22, South Carolina on February 20, the 14 Super Tuesday contests on March 3, and so forth.

Also: I now weight polls conducted partially after February 3, 2020 either 1.333 or 1.667 times higher, and polls conducted entirely after February two times higher, than polls conducted entirely before February 4, 2020.

On the night of February 3, 2020, I was sitting on my usual spot on our sofa, watching MSNBC and anticipating returns from that day’s Iowa Caucuses.

Iowa Visitor Center Sep 1990

Earlier that day, I had published my final WAPA (weighted-adjusted polling average) for the 11 declared Democratic presidential candidates, calculated four different ways (Table 1):

  • Using all 58 polls conducted since January 1, 2019
  • Using only the 45 polls released since the 1st Democratic debate on June 26, 2019
  • Using only the 21 polls released since the 5th Democratic debate on November 19, 2019
  • Using only the 15 polls released since the 7th Democratic debate on January 14, 2020

Table 1: Final Iowa Caucuses WAPA for declared 2020 Democratic presidential nomination candidates

Candidate All Polls Since 1st Debate Since 5th Debate Since 7th Debate
Biden 19.9 19.8 20.1 20.3
Sanders 18.4 18.8 21.0 22.7
Warren 17.1 18.1 15.6 15.6
Buttigieg 15.9 16.8 16.7 16.7
Klobuchar 6.9 7.3 9.1 9.7
Yang 3.0 3.2 3.6 3.9
Steyer 2.8 3.1 3.1 3.5
Gabbard 1.5 1.6 1.5 1.6
Bloomberg 0.4 0.4 0.6 0.5
Bennet 0.3 0.3 0.2 0.3
Patrick 0.0 0.0 0.0 0.1
DK/Other 13.8 10.6 8.5 5.2

Based solely on these numbers, one would reasonably draw the following conclusions:

  • United States Senator (“Senator”) from Vermont Bernie Sanders and Minnesota Senator Amy Klobuchar were rising in the polls heading into the Iowa Caucuses, as to a lesser extent were entrepreneur Andrew Yang and businessman Tom Steyer.
  • Massachusetts Senator Elizabeth Warren was declining in the polls.
  • No other candidate was moving in the polls one way or the other.

By 11:37 pm EST, however, I had grown tired of waiting for results other than successive waves of entrance polls, so I tweeted the following:

RIP, Iowa Caucuses (1972-2020)

I have defended their idiosyncrasies for decades, believing the retail aspects of campaigning there outweighed the low-turnout mischegoss of the process.

 No more.

 This is ridiculous.

 #IowaCaucuses #iowacaucus2020

I will not relitigate here the myriad problems the Iowa Democratic Party had with tabulating, validating and releasing three distinct measures:

  1. Initial headcount of support for each Democratic candidate (“Initial tally”)
  2. Post-realignment headcount of support for each Democratic candidate (“Final tally”)
  3. Allocation of “state delegate equivalents,” or SDE’s, the only measure ever previously reported

Moreover, my annoyance has abated since Monday night, primarily because I suspect these vote-reporting snafus revealed that the byzantine process of converting persons standing in rooms, then possibly standing in different parts of the room, into SDE’s has always been “riddled with errors and inconsistencies,” to quote a recent New York Times headline. And if this marks the beginning of the end of using caucuses to allocate delegates to each party’s nominating conventions, so be it; they are undemocratic, exclusionary and overly complex.

As for which states “should” come first in future presidential nominating processes, I am currently agnostic.

Three days later, we finally have near-final results from the Iowa Caucuses (Table 2):

Table 2: Near-final Iowa Democratic Caucuses results, February 3, 2020

Candidate Initial Tally Final Tally SDE’s
Biden 15.0 13.7 15.8
Sanders 24.8 26.6 26.1
Warren 18.4 20.2 18.0
Buttigieg 21.3 25.0 26.2
Klobuchar 12.7 12.3 12.3
Yang 5.0 1.0 1.0
Steyer 1.7 0.2 0.3
Gabbard 0.2 0.0 0.0
Bloomberg 0.1 0.0 0.0
Bennet 0.1 0.0 0.0
Patrick 0.0 0.0 0.0
Uncommitted 0.6 0.1 0.2

The following three tables list the arithmetic differences between each candidate’s final Iowa Caucuses WAPA and each of the three reported measures; positive values indicate better performance in the Caucuses than in the polls.

Table 3: Arithmetic difference between Initial Iowa Caucuses % of vote and Iowa Caucuses WAPA

Candidate All Polls Since 1st Debate Since 5th Debate Since 7th Debate Mean


Biden -4.9 -4.8 -5.1 -5.3 -5.0
Sanders 6.4 6.0 3.8 2.1 4.6
Warren 1.3 0.3 2.8 2.8 1.8
Buttigieg 5.4 4.5 4.6 4.6 4.8
Klobuchar 5.8 5.4 3.6 3.0 4.5
Yang 2.0 1.8 1.4 1.1 1.6
Steyer -1.1 -1.4 -1.4 -1.8 -1.4
Gabbard -1.3 -1.4 -1.3 -1.4 -1.4
Bloomberg -0.3 -0.3 -0.5 -0.4 -0.4
Bennet -0.2 -0.2 -0.1 -0.2 -0.2
Patrick 0.0 0.0 0.0 -0.1 0.0
DK/Other -13.2 -10.0 -7.9 -4.6 -8.9

Initial tally. If the Iowa Caucuses were instead the Iowa Primary, this would have been the only vote reported. On this measure Sanders, Klobuchar and former South Bend, IN Mayor Pete Buttigieg averaged 4.5-4.8 percentage points (“points”) higher in the initial tally than in their WAPA. And the closer in time the polls were to the Iowa Caucuses, the more “accurate” the WAPA.

Warren (+1.8 points) and Yang (+1.6) also overperformed their WAPA in the initial tally, albeit by smaller margins. And for Warren, older polls were more predictive than recent polls.

By contrast, former Vice President Joe Biden did an average of 5.0 points worse in the initial Iowa Caucuses tally than his WAPA. Steyer and United House of Representatives Member from Hawaii Tulsi Gabbard (-1.4 each) also performed somewhat worse than their WAPA.

Table 4: Arithmetic difference between Final Iowa Caucuses % of vote and Iowa Caucuses WAPA

Candidate All Polls Since 1st Debate Since 5th Debate Since 7th Debate Mean


Biden -6.2 -6.1 -6.4 -6.6 -6.3
Sanders 8.2 7.8 5.6 3.9 6.4
Warren 3.1 2.1 4.6 4.6 3.6
Buttigieg 9.1 8.2 8.3 8.3 8.5
Klobuchar 5.4 5.0 3.2 2.6 4.1
Yang -2.0 -2.2 -2.6 -2.9 -2.4
Steyer -2.6 -2.9 -2.9 -3.3 -2.9
Gabbard -1.5 -1.6 -1.5 -1.6 -1.6
Bloomberg -0.4 -0.4 -0.6 -0.5 -0.5
Bennet -0.3 -0.3 -0.2 -0.3 -0.3
Patrick 0.0 0.0 0.0 -0.1 0.0
DK/Other -13.7 -10.5 -8.4 -5.1 -9.4

Final tally. Only three candidates improved their vote totals after supporters of non-viable candidates shifted to a viable candidate (15% of attendees at a precinct caucus):

  • Buttigieg (+5,638 supporters; +3.7 points)
  • Warren (+2,238; +1.8)
  • Sanders (+2,155; +1.8)

These three candidates, as well as Klobuchar (-1,288; -0.4), performed better in the final tally than their WAPA, on average. As with the initial tally, WAPA using more recent polls was most predictive for Sanders, Buttigieg and Klobuchar, while WAPA using older polls was most predictive for Warren.

Biden, on the other hand, lost 2,693 supporters and dropped 1.3 points between the initial and final tallies; Yang and Steyer also lost considerable support between the initial and final tallies. For all three candidates, WAPA using earlier polls was most predictive.

Table 5: Arithmetic difference between Iowa Caucuses SDE % and Iowa Caucuses WAPA

Candidate All Polls Since 1st Debate Since 5th Debate Since 7th Debate Mean


Biden -4.1 -4.0 -4.3 -4.5 -4.2
Sanders 7.7 7.3 5.1 3.4 5.9
Warren 0.9 -0.1 2.4 2.4 1.4
Buttigieg 10.3 9.4 9.5 9.5 9.7
Klobuchar 5.4 5.0 3.2 2.6 4.1
Yang -2.0 -2.2 -2.6 -2.9 -2.4
Steyer -2.5 -2.8 -2.8 -3.2 -2.8
Gabbard -1.5 -1.6 -1.5 -1.6 -1.6
Bloomberg -0.4 -0.4 -0.6 -0.5 -0.5
Bennet -0.3 -0.3 -0.2 -0.3 -0.3
Patrick 0.0 0.0 0.0 -0.1 0.0
DK/Other -13.6 -10.4 -8.3 -5.0 -9.3

SDEs. The same pattern holds for SDEs as for final vote tally, with one minor modification.

  • Buttigieg, Sanders and Klobuchar outperformed their WAPA, with the difference decreasing with more recent polls
  • Warren outperformed her WAPA, with the difference increasing with more recent polls
  • Biden, Steyer and Yang underperformed their WAPA, with the difference increasing with more recent polls.

The bottom line. To evaluate these comparisons globally, I used the sum of the squared differences (“SSE”) between each WAPA value and the results value. Excluding “DK/Other,” Table 6 lists the SSE for each comparison; higher values indicate lower predictive power.

Polling period Initial Tally Final Tally SDEs
All Polls 136.5 240.5 224.9
Since 1st Debate 115.8 210.8 198.2
Since 5th Debate 88.3 190.4 168.0
Since 7th Debate 77.1 177.8 156.1

WAPA was most predictive of the initial tally, not surprising given that poll respondents are asked which candidate they planned to support upon arriving at the caucus site, and not about second or third choices. WAPA was also slightly more predictive of the distribution of SDEs than of the final raw tally of supporters, though neither was especially predictive.

For each reported measure, WAPA was more predictive the closer the polls were to the Caucuses; I will admit this rather surprised me, given the candidate-specific differences detailed above. One explanation is that including older polls, however low-weighted, masks late polling movement of the kind that occurred to Sanders, Buttigieg and Klobuchar.

For now, however, I will continue to report multiple versions of WAPA, if only to see if this pattern holds for later contests.

Now, on to New Hampshire!

Until next time…

The 2020 Democratic Iowa Caucuses: Final Update

[Eds. note: This post was updated at 4 pm EST on February 3, 2020 to reflect on final Iowa Caucuses poll.]

At 7 PM Iowa time (8 pm EST) on February 3, 2020, Iowans will gather in nearly 1,700 precinct-level meeting places to support their preferred candidate to be the 2020 Democratic presidential nominee. They will also participate in a range of party-related business that does not concern us here.

With the exit of former Member of the United States House of Representatives (“Representative” from Maryland John Delaney on January 31, 2020, there are now “only” 11 remaining declared candidates to be the 2020 Democratic presidential nominee. The 17 candidates who have abandoned this quest have done so with grace, class and dignity; I commend them for it.

To learn how I calculate candidate WAPA (weighted-adjusted polling average), please see here; for modifications, please see here.

Here is a photograph of the Iowa Visitor’s Center on I-80 in Rock Island I took on September 5, 1990:

Iowa Visitor Center Sep 1990


As of 4:00 pm EST on February 3, 2020, here is a breakdown of publicly-available Iowa Caucuses polls:

  • 59 since January 1, 2019
  • 46 since the 1st Democratic debate on June 26, 2019
  • 22 since the 5th Democratic debate on November 19, 2019
  • 16 since the 7th Democratic debate on January 14, 2020

Before I present my final pre-Caucuses WAPA, however, here are some words of caution.

1. Caucuses differ in key ways from primaries

In the Iowa Caucuses, voters gather in a public space to publicly declare their support for a candidate. As in, they literally divide into groups of supporters for former Vice President Joe Biden, United States Senator (“Senator”) from Vermont Bernie Sanders, Massachusetts Senator Elizabeth Warren, former South Bend, IN Mayor Pete Buttigieg, Minnesota Senator Amy Klobuchar, and so forth.  A head count is taken; this initial tally is, in effect, what pre-Caucuses polls measure. This tally has never been reported.

However, any candidate whose supporters do not comprise 15%[1] of all voters at a caucus site is deemed not “viable,” and that candidate’s supporters now must choose a new, viable candidate (or, “uncommitted”). Representatives of viable candidates attempt to persuade their friends and neighbors to caucus with them; there are already stories of candidates attempting to form “alliances” in the days leading up to the Caucuses.

Once every candidate is viable, a final tally is taken. This tally has also never been reported. Why? Because the actual purpose of these precinct-level caucuses is to identify delegates to county-level conventions, which then identify delegates to the state convention, which then identifies the 41 delegates to the Democratic nominating convention to be held in Milwaukee, WI from July 13 to July 16, 2020. Thus, what has always been reported are a projection of what percentage of those 41 delegates will be pledged to vote for each candidate at the national convention; these are known as “state delegate equivalents,” or SDE’s.

This year, though the Iowa Democratic Party has announced it will report three values Monday night (or Tuesday morning):

  • The initial statewide tally for each candidate
  • The post-viability tally for each candidate
  • SDE’s for each candidate

It is thus conceivable, if not especially likely in my opinion, there will be three different “winners” of the Iowa Caucuses—or at least, confusion over the order of finish. What is still very likely, is that only three-five candidates will get any sort of boost out of Iowa.

One other way in which caucuses differ from primaries is much lower turnout, which is especially harder to forecast with any accuracy. For example, 171,517 Democrats participated in the 2016 Iowa Caucuses, while 653,669 Iowans voted for Democratic presidential nominee Hillary Clinton that fall; general election data from Dave Leip’s invaluable Atlas of U.S. Presidential Elections. Caucus turnout was thus 26.2% of general election turnout, roughly speaking. That’s year’s New Hampshire Democratic Primary—usually a relatively high-turnout event—had 253,062 participants, fully 72.6% of that state’s vote total for Clinton.

2. Absent poll numbers

There have been fewer polls of the Iowa Caucuses this year than in any election cycle since 2004: 19 in the previous month, compared to an average of 24 during the same period in 2008-16. But one poll’s absence is more glaring than the rest: the gold standard of Iowa Caucuses polls, the Des Moines Register Iowa Poll conducted by Ann Seltzer, which FiveThirtyEight.com rates A+. The Register, in conjunction with CNN, had planned to release its final Iowa Poll at 9 pm EST on February 1, 2020. However, due to the apparent absence of Buttigieg from the list of names read to at least one poll respondent, the poll was cancelled.

This poll would have had a weight of 0.987, edging out a Monmouth College poll conducted January 23-27, 2020 (0.977) and a Siena College/New York Times poll conducted January 20-23, 2020 (0.970), for highest weight overall. My Twitter feed is filled with rumors as to what the results of the poll would have been, from a massive surge by Sanders to a surge by Warren. I would not put much credence into any of these rumors.

Well, except for one thing. Three polling firms, Emerson College (A-), David Binder Research (C+) and Civiqs (C+) have conducted multiple polls of the Iowa Caucuses in the last three weeks. Using the most recent pair of polls, here are average changes ranked from highest to lowest:

  • Buttigieg  +2.0 points
  • Sanders  +1.7
  • Warren  +0.7
  • Bennet, Patrick  no change
  • Gabbard, Yang -0.7
  • Steyer  -1.3
  • Klobuchar -1.7
  • Biden -3.0

Finally, former New York City Mayor Michael Bloomberg has been excluded from eight of the 16 Iowa Caucuses conducted entirely after the 7th Democratic debate; he averages 1.1 percentage points (“points”) in the seven polls which include him.

3. The Des Moines Register endorsement

Iowa’s largest newspaper still commands attention, particularly among undecided or not-fully-committed caucus-goers. According to FiveThirtyEight.com, the last five Democratic candidates endorsed by the Register in competitive races—1988, 2000, 2004, 2008, 2016—saw Iowa Caucuses results a median 6.0 points higher than their polling average at the time of the Register endorsement. That value drops to 4.3 if you include only data from 2000 forward. The average value, meanwhile, was an increase of 8.5 points, but that drops to 5.3 when you exclude the astonishing 21.6-point increase for North Carolina Senator John Edwards in 2004. Still, even the 2.1-point increase for Clinton in 2016 could matter in a very close contest.

On January 25, 2020, the Register endorsed Warren. This was just six days after the New York Times endorsed both Warren and Klobuchar. As you see in Table 1 below, the race in Iowa has been close for months, though there is evidence Biden and, especially, Sanders have pulled slightly ahead. Still, Warren went up in those two recent polls, and another late poll—from Data for Progress (B+/C-), January 28 to February 2, 2020—gives her 19% of the vote. Thus, a minimum 4.3-point increase for Warren is highly plausible. If it comes primarily at the expense of Sanders and Biden, it could make the difference between Warren finishing in a close top two or a more distant fourth…or even fifth, behind Klobuchar.

Table 1: Final Iowa Caucuses WAPA for declared 2020 Democratic presidential nomination candidates

Candidate All Polls Since 1st Debate Since 5th Debate Since 7th Debate
Biden 19.8 19.7 19.9 20.0
Sanders 18.4 18.8 20.9 22.4
Warren 17.1 18.1 15.6 15.5
Buttigieg 16.0 16.9 16.7 16.8
Klobuchar 7.0 7.4 9.1 9.8
Yang 2.9 3.2 3.5 3.7
Steyer 2.8 3.1 3.1 3.5
Gabbard 1.6 1.6 1.6 1.6
Bloomberg 0.4 0.4 0.6 0.5
Bennet 0.3 0.3 0.2 0.3
Patrick 0.0 0.0 0.0 0.1
DK/Other 13.7 10.5 8.7 5.7

The bottom line is this: anybody who thinks they know what will happen in the 2020 Iowa Caucuses has absolutely no idea what will happen in the Iowa Caucuses. The polling, already very difficult to do in a multi-candidate race, is extremely close—with fully four candidates above the 15% viability threshold (and a fifth not far behind), at least statewide; we have almost no sense of caucus-goers’ “backup” choices, or even who will participate; and we are lacking the definitive poll of this race. Perhaps Sanders and Biden really do have a slight edge over Warren and Buttigieg, but I would not bet anything remotely of value on it; in fact, I think Warren’s chances of finishing first or at worst a very close second are understated.

We shall see.

Until next time…

[1] Without rounding, I believe.