Reversion to the Mean?

Correction 2020-08-26 06:03 UTC: 

As it turns out, a bug I've been fighting on the site that causes data to sometimes be randomly corrupted until I notice and fix it popped up with perfect timing for me to include some bad data in the blog post below.

Specifically, only the probabilistic view was impacted this time… it had bogus numbers for Arizona, which threw everything else off. Despite a couple of warning signs, I didn't see the problem until well after the post below. Oops.

The right numbers as of when this post was made should have been:

  • Trump 2σ: Biden +50
  • Median: Biden +148
  • Biden 2σ: Biden +258

This would have made the deltas: Trump +2, Trump +4, and Trump +2, respectively. Still movement toward Trump on those metrics, but significantly less than indicated below. And Biden's win odds should have remained flat at 99.9%.

The graph for the probabilistic model trend is of course also off because of the same issue.

Apologies for the error. I'm crossing my fingers that I have finally squashed this bug, or at least that I will notice and fix specific errors before making posts that include them. Thanks for understanding:

Original post from 2020-08-25 06:51 UTC:

Time for another blog update. As always, if you are impatient for one of these updates, the 2020 pages on Election Graphs are updated nearly every day as new polls come in.

The last update here was 8 days ago on August 17th.

Here are the high-level changes since then:

Model Metric 17 Aug 25 Aug 𝚫
Categories Trump Best
Expected
Biden Best
Biden +6
Biden +182
Biden +288
Biden +6
Biden +146
Biden +288
FLAT
Trump +36
FLAT
Tipping Point Biden +5.9 Biden +6.0% Biden +0.1%
Probabilities Trump 2σ
Median
Biden 2σ
Biden +52
Biden +152
Biden +260
Biden +32
Biden +128
Biden +238
Trump +20
Trump +24
Trump +22
Trump Win
Tie
Biden Win
0.1%
0.0%
99.9%
0.2%
0.1%
99.7%
+0.1%
+0.1%
-0.2%

This week's TL;DR: While Biden is still significantly ahead, and his tipping point even improves slightly, Trump is losing by a smaller margin than he was last week.

There was only one significant category change this week. It was Ohio:

Ohio had moved into "Weak Biden" territory in mid-July. But this week it moves back to "Weak Trump".

Either way, the state is close. This move is from just barely Biden, to just barely Trump. It is really too close to call.

Trump's lead in the average is currently 0.2%. Given the historical results on Election Graphs averages from 2008 to 2016, that translates into a 56.1% chance of a Trump win and a 43.9% chance of a Biden win.

But the categorization view of things doesn't care about that. It just shows Ohio's 18 electoral votes moving from the Biden column to the Trump column, which means Biden's expected margin drops 36 EV from 182 to 146.

The change in the expected case can be seen above. After a peak for Biden in July, the expected case is back in the range it has usually been in over the last 6 months.

Before we look at the probabilistic views, here are the no-commentary views of all of the other close states (and congressional districts that give electoral votes):

Putting all of this together into our probabilistic model, you get this trend:

Looking at the center median line, where half the simulated election results were better for Biden, and half were better for Trump, Biden's most recent peak was a 180 electoral vote margin on July 31st. Biden's lead in that case is now down to only a 128 EV margin. This is down another 24 from last week.

Clearly the recent movement has been in Trump's favor. Biden's lead is still substantial though. And unlike the categorization view, it is still stronger than it was in the spring. But Trump has clearly bounced back from his July lows.

Other averages, such as Trump's approval ratings, or Trump vs Biden national polling have followed similar patterns. Namely, after a low point for Trump in June or July, the averages have reverted to more typical numbers.

As the campaigns go into high gear, the question is if the race will stay within the basic range we have seen so far this year, or if one or the other of the candidates will be able to break out.

My simulations still have Biden at a 99.7% chance to win if the election was today. (The election is not today.)

This is a very asymmetric situation. Trump needs to move things significantly in his direction to win. Biden just needs to hold his current lead. If Biden actually improves his situation, it doesn't change the outcome, it just increases Biden's margin.

Biden's tipping point lead is now 6.0%. This number represents how much polls would have to change nationally to flip the winner if the change was uniform across all states.

The RCP average of national polls is currently at a 7.6% Biden lead. This implies that the structure of the electoral college is currently giving Trump a 1.6% head start, which is unchanged from last week.

The spectrum of states where the margin is less than 10% now looks like this:

As was the case last week, in order to win Trump needs to win ALL of the close states… plus Pennsylvania.

Now comparing to this time in 2016:

<71 Days Out> 2016 2020
Expected Case Clinton by 144 Biden by 146
Tipping Point Clinton by 3.4% Biden by 6.0%

Biden is doing very slightly better than Clinton was in the "Expected Case" 71 days before the election but is doing considerably better with the tipping point.

The best Clinton saw in the Expected Case in the last 71 days was a 154 electoral vote margin in October. Biden is currently weaker than that.

Clinton's best Tipping Point in the last 71 days was 6.0% though. Biden currently matches that. But it is key to remember that Clinton's 6.0% tipping point maximum was in October, and it completely evaporated in the last month before the election.

Things can and do change based on breaking news. Biden is way ahead at the moment. If the election was today, Biden would almost certainly win.

But there are 70.7 days left to go.

The map below is where things stand today, but there WILL be more ups and downs before the end. Keep watching!

For more information:

This post is an update based on the data on the Election Graphs Electoral College 2020 page. Election Graphs tracks a poll-based estimate of the Electoral College. The charts, graphs, and maps in the post above are all as of the time of this post. Click through on any image for current interactive versions of the chart, along with additional details.

Follow @ElectionGraphs on Twitter or Election Graphs on Facebook to see announcements of updates. For those interested in individual poll updates, follow @ElecCollPolls on Twitter for all the polls as I add them. If you find the information in these posts informative or useful, please consider visiting the donation page.

Summer Doldrums

Time for another update for the blog. As always, if you are impatient for one of these updates, the 2020 pages on Election Graphs are updated nearly every day as new polls come in.

The last blog update was 8 days ago on August 9th.

Here are the high-level changes since then:

Model Metric 9 Aug 17 Aug 𝚫
Categories Trump Best
Expected
Biden Best
Trump +34
Biden +180
Biden +288
Biden +6
Biden +182
Biden +288
Biden +40
Biden +2
FLAT
Tipping Point Biden +4.2 Biden +5.9% Biden +1.7%
Probabilities Trump 2σ
Median
Biden 2σ
Biden +50
Biden +154
Biden +264
Biden +52
Biden +152
Biden +260
Biden +2
Trump +2
Trump +4
Trump Win
Tie
Biden Win
0.1%
0.0%
99.9%
0.1%
0.0%
99.9%
FLAT
FLAT
FLAT

The bottom line here is there is not much net change. If you had to pick a winner, Biden is a bit better off than when we made our last post. But really, things haven't moved all that much.

Let's start with the states that actually moved in or out of the "Weak Biden" and "Weak Trump" categories in our categorization view.

There were three:

After a brief foray into "Weak Biden" territory, Biden's lead in Pennsylvania increased once again to over 5%, moving the state to our "Strong Biden" category, and removing winning Pennsylvania from what we call Trump's "best case".

With this Trump's best case margin drops 40 electoral votes from a 34 electoral vote win to a 6 electoral vote loss.

As of our last update, Georgia had moved from just barely Biden to just barely Trump. It didn't last long. Georgia is now once again just barely Biden. "Just barely" is critical here of course. It is really just too close to call.

North Carolina had been in the "Weak Biden" category since June, but Trump has led the latest batch of polls and thus has pulled North Carolina back to his side of the line. Narrowly. Once again, the truth is the state is too close to call.

With the Georgia move, Biden's margin increased by 32 electoral votes. But the North Carolina move took away 30 of that. So the net change is a 2 electoral vote improvement for Biden in the "expected case" where every candidate wins exactly the list of states they lead in the Election Graphs averages.

The change in the expected case and in Trump's best case can be seen in the chart above.

Before we look at the probabilistic views, here is a quick no-commentary rundown of all of the other close states (and congressional districts that give electoral votes):

Putting all of this together into our probabilistic model, you get this trend:

Looking at the center median line, where half the simulated election results were better for Biden, and half were better for Trump, Biden's most recent peak was a 180 electoral vote margin on July 31st. Since then he has slipped down to a 152 electoral vote margin. So the recent movement has been against Biden.

Maybe this trend will continue. Or maybe things will bounce back in Biden's direction again. In this view, it now looks like things have been staying within a fairly narrow band since the end of June. But we're now at the upper end of that band. Trump may break out.

Conventional wisdom is that there are "convention bounces". And we are about to enter two weeks of political conventions. But this year the conventions are essentially back to back. So if there are such bounces, the Trump bounce may just cancel out the Biden bounce too quickly to even be measured reliably in state-level views such as we have on Election Graphs.

The conventions do however tend to be the point at which both campaigns go into overdrive and non-political folks finally start paying attention to the race. So it would not be surprising to have significant events that move the needle.

As usual, we'll just have to wait and see.

My simulations still have Biden at a 99.9% chance to win. This graph has been quite boring for some time now because Biden has the blue pegged up against the 100% line.

As always, the important caveat that this is if the election was today, which it is not.

There is time for this to change. So how secure is the Biden lead?

Biden's tipping point lead had dropped down to 4.6%, but it has rebounded to 5.9%. This number basically represents how much polls would have to change nationally to flip the winner if the change was uniform across all states.

By comparison, the RCP average of national polls is currently at a 7.5% Biden lead. So it would take a 7.5% move for Trump to win the popular vote, but only a 5.9% move for Trump to win the electoral college. This implies that the structure of the electoral college is currently giving Trump a 1.6% head start.

It is tempting to concentrate on the states that are currently closest. At the moment that would be Iowa, Maine CD2, North Carolina, Ohio, and Texas. But at the moment if Biden won those states it would just be gravy on top of a win that had already been secured. And if Trump won those states, it would not be enough to win the election.

The battle for winning the election is around the tipping point. You want to be as far ahead as possible in the states near the tipping point. That is how you secure the win, and that is generally where most efforts should be concentrated.

Right now, Pennsylvania is the tipping point. Adding in the two states on either side, you bring in Michigan, Wisconsin, Nevada, and Florida.

This is part of why you see tons of polls in Pennsylvania, Michigan, and Wisconsin even though none of those are particularly close at the moment. And of course, Florida, since it is not that far off from the tipping point, AND it is close at the moment.

It does not however explain why there have only been five polls in Nevada in the LAST YEAR. Come on people! Can we get some polls in Nevada?

Anyway… you can see how the tipping point fits in with all the other states in the current spectrum of the states in contention:

So yeah. As with 2016, watching Michigan, Wisconsin, and Pennsylvania makes sense.

Arizona? Georgia? Ohio? Iowa? North Carolina? Texas?

Those are "stretch goals" for Biden. Great as a bonus, but he needs to concentrate on the bread and butter first.

By contrast, Trump NEEDS all those states… plus some. At the moment Trump can once again win ALL of the close states and still fall slightly short. He needs to also bring Pennsylvania back into the fold to win.

How do the metrics compare to where things were at this time in 2016?

<79 Days Out> 2016 2020
Expected Case Clinton by 86 Biden by 182
Tipping Point Clinton by 3.0% Biden by 5.9%

By both metrics, Biden is doing significantly better than Clinton was at the same point in the race four years ago.

The best Clinton saw in the Expected Case in the last 79 days was a 178 electoral vote margin near the end of August. Biden is slightly ahead of that mark as well.

Clinton's best Tipping Point in the last 79 days was 6.0% though, which she didn't hit until October. Biden is below that level, and that 6.0% tipping point lead disappeared in less than a month in 2016.

So that serves as the usual warning of how quickly things can change.

Finally, the current map:

78.7 days until polls start to close on election night, and the conventions are about to begin. The race is about to go into overdrive. Buckle up!

For more information:

This post is an update based on the data on the Election Graphs Electoral College 2020 page. Election Graphs tracks a poll-based estimate of the Electoral College. The charts, graphs, and maps in the post above are all as of the time of this post. Click through on any image for current interactive versions of the chart, along with additional details.

Follow @ElectionGraphs on Twitter or Election Graphs on Facebook to see announcements of updates. For those interested in individual poll updates, follow @ElecCollPolls on Twitter for all the polls as I add them. If you find the information in these posts informative or useful, please consider visiting the donation page.

Trump Narrows The Gap

I am overdue for another update. The 2020 pages on Election Graphs are updated nearly every day as new polls come in. So you can always see the current status there for yourself in between these posts. But here comes another blog post…

Since the last update on July 24th, there have been new state polls in Pennsylvania (x8), Arizona (x7), Florida (x7), Michigan (x10), Ohio (x5), North Carolina (x9), South Carolina (x4), Minnesota (x5), Colorado (x3), Georgia (x5), Texas (x4), Virginia (x3), Wisconsin (x9), New Jersey, Massachusetts, Alaska, Iowa (x5), Maine All (x4), Montana (x2), Maine CD1 (x2), Maine CD2 (x2), Washington, New Hampshire (x3), California, Alabama, Kentucky (x4), Hawaii, Indiana, Oklahoma, Utah, and Kansas.

That's 31 out of the 56 entities that allocate electoral votes in only 16 days. That's more than half. Given that, I'm going to stop calling out the states with polls each update. In short, the answer from now until the election is always going to be "a lot of them", and "multiple polls for all the close states".

It has been 16 days, how much has changed?

First the summary table of changes:

Model Metric 24 Jul 9 Aug 𝚫
Categories Trump Best
Expected
Biden Best
Biden +36
Biden +168
Biden +288
Trump +34
Biden +180
Biden +288
Trump +70
Biden +12
FLAT
Tipping Point Biden +6.5 Biden +4.2% Trump +2.3%
Probabilities Trump 2σ
Median
Biden 2σ
Biden +80
Biden +168
Biden +272
Biden +50
Biden +154
Biden +264
Trump +30
Trump +14
Trump +8
Trump Win
Tie
Biden Win
0.0%
0.0%
100.0%
0.1%
0.0%
99.9%
+0.1%
FLAT
-0.1%

So compared to 16 days ago, what is the TL;DR summary?

Biden still leads by a large margin and actually improves his margin in the "everybody wins every state where they lead the average" expected case metric, but overall Trump has managed to reduce Biden's margin in a number of states, thus increasing the likelihood he might steal those states back and strengthening his position. And if he managed to flip ALL the close states, he could once again pull off a narrow win.

Now some of the charts, starting with the categorization view:

We can see that while Biden improved his expected case, Trump's best case has improved significantly.

So which specific states changed?

First, it was Iowa that moved from barely Trump to barely Biden, improving Biden's margin in the case where each candidate wins every state where they lead the average. But Biden leads Iowa by only 0.2%. And it looks pretty likely that the lead is due to a single outlier poll that showed a 6% Biden lead. So far no other polls indicate a Biden lead of that magnitude. So it would not be surprising at all to see Iowa slip back to the Trump side with the next poll, or at least when that outlier slips out of the average.

But then there is Florida. Biden's substantial lead in Florida has slipped significantly. He still leads, but no longer by huge margins. In our average Biden now only leads Florida by 3.0%. If the election was today, we estimate that translates into a 73.8% chance that Biden would win the state. But we actually have 86 days until the election, and there is plenty of room for this to move further.

The substantial swings here over June and July indicate that as polarized as things tend to be these days, there is still a non-trivial group of voters who have shown they can change their minds over time. In this case, they moved away from Trump for a while, but seem to be coming home again, once again putting Florida within Trump's reach.

Much the same pattern has played out in Pennsylvania. Biden built a substantial lead in June, but over the course of July, it faded quite a bit. Biden still leads Trump by 4.2% in Pennsylvania, translating into an 84.9% chance of winning the state in our model if the election was today. But that is significantly less certain than the 98.8% we had at Biden's peak.

Given Florida's 29 electoral votes and Pennsylvania's 20 electoral votes, together these states can change the margin by a massive 98 electoral votes.

Having these two states close enough to be in play is critical to Trump. At the moment, he is still behind, but close enough that it is easy to imagine scenarios where Trump could come back from behind and win them.

Not all of the movement was bad for Biden.

In Wisconsin, at the time of the last update, Wisconsin had flipped from "Strong Biden" down to "Weak Biden". But that didn't last long, and Wisconsin is once again a strong enough Biden state that we don't include it in Trump's best case. (At an 8.6% lead, our odds estimate is a 99.1% chance of a Biden win if the election was today.)

New Hampshire also moves out of Trump's reach with Biden leading the average by 7.8%, which would be a 98.6% chance of a win if the election was today.

But Wisconsin and New Hampshire are only 14 electoral votes, compared to 49 electoral votes for Florida and Pennsylvania. So the net change is 35 electoral votes in reach for Trump that were not when we did the last blog post, meaning a 70 electoral vote increase in Trump's best case.

So, now to dash through the "weak" states that are in play that didn't switch broad categories this time around, in order by  the number of electoral votes:

When you mash all of these movements together into our probabilistic model that doesn't just say that since one candidate is ahead in a state they are going to win it, but instead simulates many possible election results recognizing that close states can go either way, you get these trends:

Roughly speaking, the darker the color, the more likely the final margin will be in that range.

Looking at the center median line, where half the simulated election results were better for Biden, and half were better for Trump, Biden's most recent peak was a 180 electoral vote margin on July 17th. Since then he has slipped down to a 154 electoral vote margin.

All of the other bands have moved toward Trump as well, each to a differing degree. The moves aren't as dramatic as the categorization view shows, but there has been a steady deterioration for Biden since that peak.

June and the first half of July were a constant stream of bad news for Trump, and his position in election polls reflected that. Since then things have slowly been moving back in his direction.

To be absolutely clear, Biden still has a huge advantage. But less so than he did a few weeks ago.

It is still too small to see directly on the chart, but Biden's chances of winning when we did our last update rounded to 100.0% (it was actually 99.9931% in our simulation), and now they round to 99.9% (it is actually 99.9265% in our current simulation).

So that is still substantial, even if it is less than it was.

But that is if the election was today.

How vulnerable is that lead?

Biden's tipping point lead peaked at 7.3%. It is down to 4.2%. That's a 3.1% decline in a little over a month. If that trend continued, in another month Biden would still have a lead, but it would be quite tenuous.

That is not a prediction. It seems more likely that if Biden's spike in June was just an aberration and things are returning to the mean, that the tipping point will settle out between a 2% and 4% Biden lead.

But that is the level of lead that might just be a systematic polling error. Or that could be erased by a major event in the last few days of the campaign, too late to be measured by the polls.

So how does this look compared to 2016?

<86 Days Out> 2016 2020
Expected Case Clinton by 164 Biden by 180
Tipping Point Clinton by 6.0% Biden by 4.2%

So Biden is ahead of Clinton at this same point in time in terms of expected margins if all the states fell where their polls indicated. But Clinton's lead was actually a bit more secure than Biden's is right now, and of course, it slipped away before the end.

If the election was today, Biden would almost certainly win. But his lead is somewhat precarious. If 2% or 3% of people change their minds from Biden to Trump in a few critical states, Trump takes the lead.

Now the spectrum of battleground states :

Here is what it looked like in our last update:

And here it is today:

Out of the close ("weak") states, Biden only has to hold Arizona and Pennsylvania. He can afford to lose all the rest and still win.

But we're once again in a position where with a sweep of all the close states, Trump could win.

Finally, the current map:

86.0 days until polls start to close on election night. Stay tuned!

For more information:

This post is an update based on the data on the Election Graphs Electoral College 2020 page. Election Graphs tracks a poll-based estimate of the Electoral College. The charts, graphs, and maps in the post above are all as of the time of this post. Click through on any image for current interactive versions of the chart, along with additional details.

Follow @ElectionGraphs on Twitter or Election Graphs on Facebook to see announcements of updates. For those interested in individual poll updates, follow @ElecCollPolls on Twitter for all the polls as I add them. If you find the information in these posts informative or useful, please consider visiting the donation page.