Nevada Democratic Caucuses and South Carolina Republican Primaries: The New State of the Race

Yesterday, 735,000 Republicans in South Carolina and about 80,000 Democrats in Nevada1 headed to the polls and voted or caucused in the third day of voting in this year’s primary cycle. Here, we break down what exactly happened yesterday and what it means going forward.
South Carolina Republican Primary

Coming out of New Hampshire, Donald Trump had won big, John Kasich pulled out a surprising second place finish, Jeb Bush was riding high on beating Marco Rubio, who was suffering after an embarrassing debate performance, and Ted Cruz still confident after his win in Iowa. New Hampshire and Iowa had served to narrow the field a bit, forcing Mike Huckabee, Rick Santorum, Carly Fiorina and Chris Christie out. In South Carolina, Trump looked poised to pull off another large victory, leaving Cruz and Rubio vying for third and Bush just not wanting to finish too far behind them. Kasich had absolutely no expectations going in and Ben Carson is somehow still running. And, as expected, Donald Trump ended up the big winner of the night.

Candidates Pct. Delegates
D. Trump 32.5%
M. Rubio 22.5%
T. Cruz 22.3%
J. Bush 7.8%
J. Kasich 7.6%
B. Carson 7.2%

Trump won all of the delegates from yesterday’s contest, giving him a big lead heading into the Nevada Republican Caucuses and Super Tuesday. Rubio and Cruz ended up pretty much tied, but more importantly, Rubio showed that he has mostly recovered from his poor debate performance and is once again the conventional wisdom establishment-backed candidate. More unfortunately for Cruz, South Carolina is an example of why the delegate math is going to be challenging for him; Ted Cruz is expected to do best in many Southern states going forward, a large chunk of which are winner-take-all in each congressional district, meaning that a close second may not mean much in terms of actually winning him delegates.

But the biggest news coming out of South Carolina on the Republican side is that Jeb Bush has announced he is suspending his campaign. This is significant for two reasons. Although there are myriad think pieces dissecting why the Bush campaign failed, I will a chart which contains just one more reason.

Jeb Bush's Advertising

This chart adds together all of the advertising minutes from Iowa, New Hampshire and South Carolina of TV ads from both the Bush campaign and Right To Rise, Bush’s primarily supporting SuperPAC. The biggest take away is that the campaign failed to really advertise until Bush had largely slipped in the polls and had little chance of recovery. It poured money into the first three states, but only right before they were to vote, meaning that they could only sway late-breaking voters. While there certainly are many late-breaking voters, they tend to vote strategically, meaning that if their primary focus is say, stopping Trump, they are more likely to vote for someone like Rubio than Bush. Bush’s advertising campaign simply came too late to substantially change public perception of him as a viable candidate.

Bush’s dropping out is significant for both electoral and monetary reasons. On the electoral side, it frees up the “establishment lane” of the GOP. With Bush and Christie now both out, more moderate, establishment-minded Republican voters really only have a choice between Kasich and Rubio. Taking a look at polling2, we can see specifically that this helps Rubio the most.

Jeb Bush Supporters Second Choice

We can then take the 6.3% of support that Bush had in the latest HuffPost Pollster average and split it up to the different candidates.

Polling with Bush support split up.

Clearly, Rubio is the biggest beneficiary to Bush dropping out, but that 6.3% being split multiple ways means that it honestly does not have a huge difference on pure polling numbers.

The second effect of Bush dropping out, freeing up big donors, is much more significant. Although Bush never got very far off the ground enticing voters, he was very successful in enticing donors. However, with him out of the race, many of these donors will be able to move their money around freely. And the general thinking is that many will move their money over to Rubio who can then use it to execute the same kind of attack-ad heavy campaign that allowed Romney to knock out his rivals in 2012.

Ultimately, the general thinking is that Bush’s dropping out leaves more room for Rubio to win over establishment support and use that support to win the nomination. However, with Trump and Cruz still putting up strong performance, even if Cruz cannot win many winner-take-all states, it seems increasingly likely that this race will drag on well past Super Tuesday.

Nevada Democratic Caucuses

On the Democratic side, yesterday brought more of a return to status quo than any substantial change. Although Bernie Sanders did better than expected in Iowa against Hillary Clinton and followed it up with a demanding victory in New Hampshire, Hillary Clinton has steadily been a strong favorite to win the nomination. Going into Nevada, it seemed as if some nebulous “momentum” might be on the side of Sanders, although little was certain because of a dearth of polling in the state. However, Hillary Clinton pulled off a convincing win over Sanders.

Candidates Pct. Delegates
H. Clinton 52.7%
B. Sanders 47.2%

Although her victory was not the 20+ point lead that was seen in the polling last fall, reflecting the overall growth of Sanders as a competitor to Clinton, it likely effectively stopped any momentum that Sanders had coming out of New Hampshire and Iowa. And heading into South Carolina, it will likely prevent the downward trend in Clinton’s polling there that she has experienced since December. Nevada also showed that Clinton’s lead among Latino voters is not as commanding as it was eight years ago3 and South Carolina will let us know if her lead over Sanders among Black voters is as strong as it is assumed to be.

All in all, the Nevada caucuses did very little to change the Democratic race drastically; rather, it restored it back to the conventional wisdom that Clinton will win the nomination. South Carolina will be another test of this hypothesis. If Clinton is able to come away there with a commanding lead, she will have the momentum, and demographics, behind her.

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New Hampshire Results and the Limitations of Data Analysis

Before the Iowa primary, we showed the data behind the conventional wisdom that outperforming expectations in Iowa generally leads to a polling bump in New Hampshire.  The logic behind this argument makes perfect sense, as positive media coverage and the bandwagon effect attracts voters who are still making up their minds.  And plotting the data from the last few elections, we were able to see a clear positive trend in support of this theory.  However, the recent New Hampshire results demonstrate an important but often overlooked truth about poll-based predictions – they assume the status quo remains unchanged.  The poll averages that many media predictions are based on do a decent job of measuring current support, but they simply cannot account for future events that have nothing to do with the numbers.  So when a surging candidate like Marco Rubio trips up in a debate with heavy media attention, all our predictions go out the window.

For all the uncertainty on the Republican side of things, our simplistic model of converting Iowa support to New Hampshire success actually worked quite well for the Democrats.  We first calculated the percent that Bernie Sanders overperformed and Hillary Clinton underperformed against expectations in Iowa.  To calculate the expectations, we modified the HuffPost Pollster average with corrections for both the viability rule that hurt Martin O’Malley’s final vote tally as well as for undecided voters1.  Using this calculation as our baseline, we found that Bernie Sanders overperformed by 1.2% and Hillary underperformed by 0.6%.  In our article on Iowa, we explained that in the last few elections, each percentage point above expectations in Iowa tends to raise New Hampshire performance by 0.55%.  This allowed us to calculate, using our historical model2, a prediction for the New Hampshire vote and compare it to the actual results:


HuffPost Pollster Average Average Adjusted for O’Malley + Undecideds Actual Result Result against Expectations
Sanders 44.6 48.4 49.6 +1.2
Clinton 47.7 50.5 49.9 -0.6


New Hampshire

HuffPost Pollster Average Feb. 1st Average Adjusted for O’Malley + Undecideds Actual Result Model’s Predicted Result
Sanders 54.7 58.4 60.4 59.1
Clinton 39.4 41.8 38 41.4

All in all, the historical model was fairly accurate at predicting the actual New Hampshire results, missing by just 1.3% for Sanders and 3.4% for Clinton. While the magnitude of the shift was slightly larger than predicted by our model, the model was successful in adjusting the expectations in the correct direction for both candidates.  The relative success of the model for the Democrats was likely caused by the Democratic race progressing more or less how the model’s assumptions predicted them to.  Sanders’ campaign beat expectations in Iowa, received energetic press, and saw a small bump in New Hampshire.  The Clinton campaign faced media questions about the rising threat of Sanders, and saw a small drop in support in New Hampshire.

The Republican results in New Hampshire, however, defied the expectations set by our model as well as most political pundits.  Most pundits declared that Marco Rubio and Ted Cruz beat expectations in the Iowa caucus, while Donald Trump underperformed.  Following conventional punditry as well as our quantitative model, we would thus expect Rubio and Cruz to see a bump in support in New Hampshire while Donald Trump’s numbers fell.

In actuality, the exact opposite happened.  Trump’s final results actually surpassed his New Hampshire HuffPost polling average from the day of the Iowa caucus, even though his campaign had to fight off negative media attention arguing many of his supporters were unlikely to turn up at the polls. Meanwhile, Rubio’s and Cruz’s final vote tallies were lower than their polling averages a week earlier.  What happened?  Well, to put it simply, events happened that broke the assumptions made by both our model and the political pundits.  Our model predicted that momentum from Iowa for someone like Rubio would carry on to positively influence his level of support in New Hampshire.  And this prediction seemed to be coming true, as Rubio’s HuffPost polling average in New Hampshire was climbing the week before the primary.  However, an unforeseen and unpredictable debate gaffe likely cost him supporters in the crucial few days before votes were actually cast.  Cruz faced favorable demographics in Iowa but unfavorable demographics in New Hampshire, likely playing a role in his disappointing finish.  And Trump’s surprisingly high turnout proved to the media once again that it is notoriously difficult to compare Trump’s supporters with historical examples.

So, in conclusion, New Hampshire’s results show that while our models and punditry occasionally get it right, both attempts at political prognostication work best when certain assumptions hold.  The Democratics had no last-minute surprises, and estimates were pretty close to the final result.  However, the last-second poll swings of the Republicans demonstrate that even the so-called experts base their predictions on imperfect assumptions, and it’s sometimes best to take both polls and pundits with a grain of salt.


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