Most polls and FiveThirtyEight predict a Clinton blow-out on Tuesday, with her winning all five states, in some cases by a large margin. My model, however, predicts that each candidate will win a subset of these states, but with Clinton still win the day.
I’ve been working on a model to predict primary outcomes for the Democratic selection process, and generally, the model has proved very effective. After each set of primaries I’ve adjusted the model to try to do a better job of predicting the upcoming contests. The most important adjustment is the one that affects the current model.
The model assumes that we can predict voting behavior by ethnicity. Given this assumption, the distribution of potential Democratic participants by ethnic group then gives the final likely division among primary voters or caucus goers across the two candidates, then this translates directly into the division of committed delegates for that state. The estimates of within-group voting are made from exit polls.
The most recent revision divides states into “Southern” (meaning deep south) and “Not Southern,” and uses different sets of numbers for each of the two kinds of states.
To date, about 32% of the committed delegates have been assigned, with 769 for Clinton and 502 for Sanders. Next Tuesday, March 15th, an additional 691 delegates will be committed to the two candidates. So, almost exactly 50% of all the delegates for the entire process will be committed. (None of this counts uncommitted delegates, sometimes called “Super Delegates.”)
If Clinton and Sanders each do about as well as they have done in the past, this will leave Sanders with a significant gap to close, and he probably can’t win the nomination. If Clinton does better, that closes the door to Sanders even more firmly. But, if Sanders does well, that may help close the gap and considering Sanders as a possible nominee is reasonable.
The current model, which has the interesting dual property of giving Sanders more delegates than the polls currently predict, but also, according to my own evaluation of my own model, probably underestimates Sanders’ performance, suggests that Clinton will earn more delegates than Sanders, but not by too much. So, if the underperformance of the model is strong enough, they could come close to a tie. At present, here are my predictions for the outcome of Tuesday’s set of primaries:
Florida: Clinton will win but by less than expected. The outcome will be so close that I can’t rule out a Sanders win here.
Illinois: Sanders will win, but this may be close to a tie.
Missouri: Sanders may win by a small margin. However, keep in mind that it is very difficult to classify Missouri as a “Southern” vs. “not-Southern” state. I picked “Not-Southern” for this prediction. But we’ll see. If Missouri goes all “Southern” then Clinton wins there.
North Carolina: Clinton will win by a very large margin (70-something to 30-something delegates).
Ohio: Sanders will win by a small margin.
If these numbers are close to what happens, or if Sanders does better, then Sanders is still in the race, though with a tough road ahead of him. If, in contrast, the polls turn out to be right, it would indicate that Sanders’ over performance in earlier contests may have been temporary, and the chance of him winning the primary is very small. At present the polls show Clinton way ahead in Florida, Clinton barely ahead in Illinois, a near tie in Missouri, Clinton way ahead in North Carolina, and Clinton a little ahead in Ohio. In other words, I’m suggesting that Sanders will win three out of the five races, while the polls suggest he will one or may be two.
Let’s look at the FiveThirtyEight predictions to see how they compare.
FiveThirtyEight gives Florida to clinton (nearly 100% chance of wining). They predict a strong Clinton finish in the state, about 2:1.
For Illinois, FiveThirtyEight says about the same, a better than 2:1 projected result, with Clinton carrying away a lot of the delegates.
For Missouri, FiveThirtyEight has Clinton probably winning, but not by too much, so only a small pickup for her.
For North Carolina, FiveThirtyEight has Clinton winning just shy of 2:1 over sanders.
For Ohio, FiveThirtyEight predicts a Clinton win, and a fairly strong one.
So we can see that there is a huge difference between FiveThirtyEight’s prediction and mine, and the two methods are very different. Both of the methods used by FiveThirtyEight rely on some combination of opinion or support-related information, while my method uses none of that. For this reason it is not surprising that the two methods produce very different results.
The point of going over the FiveThirtyEight predictions is that they do a very good job of representing the polling data, which overall strongly suggest that Clinton will run away with the nomination. The problem is, these data have been suggesting this since Iowa, and generally speaking, Sanders has far outperformed those estimates.
The final outcome in terms of delegates from all five races will be approximately:
Clinton: ca 364 delegates
Sanders: ca 326 delegates
This will mean that, at the end of the day Tuesday, Hillary Clinton will have about 56% of the committed delegates, to Sanders’ 44%, with about 50% of the committed delegates assigned.