Showing posts with label convention bounces. Show all posts
Showing posts with label convention bounces. Show all posts

Sunday, August 23, 2020

One Thing About Convention Bounces

This first thing that FHQ does every four years -- if not more often -- around national convention time is go back and consult Thomas Holbrook's classic, Do Campaigns Matter? on the matter of convention bounces. Yes, there are more recent treatments of the phenomenon, but this one was integral to my formative thoughts on what a candidate may gain -- or in some cases lose -- in the aftermath of their national conventions.

One such updated notion is that in an era of increased polarization between the two major parties, the bump is much reduced compared to earlier cycles (those during the latter half of the 20th century, say). And that does seem to hold up for the most part. Since the turn of the 21st century, these convention bounces have been more muted. There are far more one and two point changes and far fewer bounces approaching double digit gains, for example.

But as some of the Sunday morning show chatter naturally turned to the impact of the virtual Democratic National Convention this past week, FHQ was left with one seemingly important question: Does a bounce depend at all on where a candidate began? In other words, if a candidate starts convention week at 40 percent, then does that candidate receive a larger bounce than someone who entered their convention at 49 percent, for example?

Hypothetically at least, the higher a candidate's standing heading into their convention, the lower the bounce would be expected to be. At least that was my thought before looking at the data (a limited version of it anyway). The American Presidency Project has the data on the bounces the two major party candidates have received since the 1964 cycle. And while Holbrook has some exploration of a candidate's pre-convention standing in the polls in his book, it relies on the share of the two party level of support. I wanted to look at it based just on where the candidates stood in public opinion polling the day before their convention commenced without that adjustment. That includes support for other candidates and undecideds; some measure of any given candidate's room for improvement (the pool from which they will draw their bump).

For that pre-convention starting point, then, FHQ turned to the archives of the Real Clear Politics averages of national presidential trial heat polls dating as far back as those go. No, going back to only the 2004 cycle is likely not the rigorous examination that everyone would prefer, but this is a quick and dirty (first glance) look at the bivariate relationship between a candidate's starting position and the bounce they received from their convention.

And when one regresses the starting positions of the eight candidates across those four cycles on the bounces they got out of them, well, the results are not terribly revealing. For starters, there really is not that much of a relationship between the two.



In fact, at an R2 0.075, there is next to no relationship at all. But the relationship is in the hypothesized direction: negative. As a candidate's pre-convention share rises, that candidate's expected bounce decreases. More precisely, a one point increase in a candidate's standing in the polling averages the day before the convention starts decreases the bounce for that candidate, post-convention by 0.35 points. On the surface that appears at least substantively significant (without being at all statistically significant). But one has to consider the range of the independent variable. That is the gum in the works here. If not for Trump's 40.6 percent share in the RCP averages before the 2016 Republican convention in Cleveland, the range would have run from McCain's 44.2 percent share in 2008 to Obama's 46.4 percent level of support in 2012. That is seven candidates clustered into a range of just around two points.

And that brings this discussion full circle because the reason FHQ even thought about this potential relationship is due to Biden's standing heading into last week's convention. Over these last four cycles, the former vice president's 50.2 percent share in last Sunday's RCP averages was head and shoulders above every other candidate since 2004. It is nearly double the range in the data discussed above (minus the Trump outlier).

Biden's position could also be considered an outlier in the data. However, using that (admittedly weak) regression model above, the predicted bounce for a candidate with a 50.2 percent share heading into a national convention is 0.25 points. And that is not too distant from the "no bounce" many pundits are talking about when looking at the handful of post-convention polls that have been released.

Furthermore and for what it is worth, Trump's standing as of now -- August 22 data -- at RCP is 42.4 percent. The predicted bounce for a candidate beginning convention week there is right under three points. But take that with a huge quarry-full of salt grains. Again, this was just for fun. But it was interesting on some level.

The key in all of this remains the fact that in the 21st century Biden entered the convention last week at a level that we just have not witnessed. And it is worth questioning exactly how much a candidate in that position would gain in an era when many/most are lock in on their team's candidate.


--
Recent posts:
The Electoral College Map (8/22/20)

The Electoral College Map (8/21/20)

The Electoral College Map (8/20/20)


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Monday, September 22, 2008

About Those Zogby Interactive Polls...(The McCain Bounce Revisited)

As I alluded to a week ago, I wanted to examine the post-convention bounce McCain enjoyed without the seemingly over-inflated numbers from Zogby's internet polling outfit. Why? Well again, I did this same thing with the post-clinch bounce Obama had throughout June. The first wave of Zogby state polling was seemingly overly supportive of Obama and really skewed the bounce the Illinois senator got in his favor. The underlying message is that the polling that Zogby has been doing through voluntary online surveys seems to drift with the political winds. That may not be a fair characterization since the first wave involved 34 states total, while the second and third waves have been pared down to ten or so battleground states. It may not be fair, but I'll stick with that description for the time being.

Well, what were the results (...of these now week and half old polls)?

Zogby Interactive -- Wave Three (Sept. 9-12)
StatePollMargin
Colorado
Zogby Interactive
+2
Florida
Zogby Interactive
+10.3
Michigan
Zogby Interactive
+5.7
Missouri
Zogby Interactive+6.1
Nevada
Zogby Interactive
+7.6
New Hampshire
Zogby Interactive
+6.3
New Mexico
Zogby Interactive
+1.5
North Carolina
Zogby Interactive+1.5
Ohio
Zogby Interactive
+5.9
Pennsylvania
Zogby Interactive
+4.8
Virginia
Zogby Interactive
+6.5

There is a lot of red on that list and surprisingly that red stretches into a trio of states, Colorado, New Hampshire and Pennsylvania, that are currently among the group of Obama toss ups. North Carolina, once again, has a result contrary to what has been witnessed throughout other polling recently. That has been the mark of Zogby's efforts in the state across the three iterations of surveys, though. Finally, Michigan of all states is apparently immune to the red drift in many of these states, turning in a solidly blue 5.7 point margin for Obama.

That's all well and good, but what effect did these poll have on the electoral college map? Nothing really. Not one of these states changed categories and that can be attributed largely to the number of polls that have been done in all these toss up states and New Mexico over the entire campaign. With an increasing amount of polling activity in the most competitive states, outliers are absorbed into the backend of the weighted average with little, or in this case no, effect. But while the electoral college was left unchanged, the assessment of the bounce the McCain-Palin ticket got out of the GOP convention did not. The picture without these polls from Zogby was a bit mixed. McCain gained, especially in traditionally Republian states that had been closer than history would indicate prior to the convention. However, his momentum in FHQ's toss up states was less pronounced. The Arizona senator had the averages moving in his direction in seven of the 11 toss up state, but Obama still had New Hampshire, Pennsylvania, Missouri and Indiana moving toward him since the pre-convention baseline was set on August 24.

[Click Map to Enlarge]

But New Hampshire and Pennsylvania were among the Zogby polls that showed a McCain lead. They were and both those polls had the effect of shifting the averages in the Arizona senator's direction. In Nevada and Ohio the bounces increased as well, moving from the "barely moved" range into the middle category of movement -- a one to two point change in the average over the convention period and its aftermath. All was not lost for Obama, however. Based on the strength of Zogby Michigan poll, the trend in the Wolverine state began to favor the Illinois senator. And the surprising Obama lead in North Carolina helped mute the effect McCain got out of his convention in North Carolina.

Given that we see such volatile changes based on a series of polls that may not be all that representative, why include them at all? A valid question. One that I'll answer with another question: What happens to the weighted averages when we back out all three waves of Zogby polling? If the effect is minimal, no harm, no foul, right? But if there is a decided shift toward one of the candidates, then the idea of the polls' inclusion may need to be revisited. Since the first two waves were seen as favorable to Obama, it could be hypothesized that McCain would stand to benefit from those polls being omitted.

Here is the electoral map from today:
[Click Map to Enlarge]

And here is how the map would look tomorrow if the Zogby polling were dropped from the averages (Huh? Tomorrow? How does that square with the map for today? This gives you a sneak peek for tomorrow's update. It includes the polling released today, all 18 polls from 15 states.):
[Click Map to Enlarge]

Yeah, that's it. North Carolina is the only state that changes categories based on the three waves of Zogby polling being dropped. But as we have seen, changing the color on one state on a map doesn't really provide us with the full picture.

The Electoral College Spectrum*
HI-4
(7)**
MA-12
(157)
CO-9***
(269/278)
ND-3
(160)
KS-6
(64)
VT-3
(10)
WA-11
(168)
NH-4***
(273/269)
WV-5
(157)
NE-5
(58)
RI-4
(14)
IA-7
(175)
NV-5
(278/265)
SC-8
(152)
AR-6
(53)
IL-21
(35)
MN-10
(185)
OH-20
(298/260)
AK-3
(144)
TN-11
(47)
CT-7
(42)
OR-7
(192)
VA-13
(311/240)
TX-34
(141)
KY-8
(36)
NY-31
(73)
NJ-15
(207)
IN-11
(322/227)
GA-15
(107)
AL-9
(28)
CA-55
(128)
WI-10
(217)
FL-27
(349/216)
SD-3
(92)
WY-3
(19)
MD-10
(138)
NM-5
(222)
MT-3
(352/189)
MS-6
(89)
OK-7
(16)
ME-4
(142)
MI-17
(239/316)
MO-11
(363/186)
LA-9
(83)
ID-4
(9)
DE-3
(145)
PA-21
(260/299)
NC-15
(175)
AZ-10
(74)
UT-5
(5)
*Follow the link for a detailed explanation on how to read the Electoral College Spectrum.
**The numbers in the parentheses refer to the number of electoral votes a candidate would have if he won all the states ranked prior to that state. If, for example, McCain won all the states up to and including Pennsylvania (all Obama's toss up states, but Michigan and New Mexico), he would have 299 electoral votes. Both candidates numbers are only totaled through their rival's toss up states. In those cases, Obama's number is on the left and McCain's is on the right in italics.

***
The line between Colorado and New Hampshire is the where Obama crosses (or McCain would cross) the 270 electoral vote threshold to win the presidential election. That line is referred to as the victory line. Both states are currently favoring Obama, thus the blue text in those two cells.

As we look at how the Electoral College Spectrum and Watch List would look with today's polls included, but the Zogby polls omitted, what we see is that there are not that many changes, but what changes there are, are almost wholly within Obama's coalition of states. Maine, Maryland and Massachusetts all saw decreases in their respective averages. Not enough, to warrant any worry from the Democrats or joy from Republicans, but noticeable changes for states that have remained largely unchanged over the summer. The biggest shake up is among the Obama lean states. Of those, only Washington kept its same position, close to being a strong Obama state. Iowa came out stronger without the Zogby polls in the equation, jumping New Jersey, Oregon and Minnesota. Without the June Zogby poll, Minnesota also inches even closer toward being competitive as measured by FHQ's weighted average.

The Watch List*
StateSwitch
Alaskafrom McCain leanto Strong McCain
Delawarefrom Strong Obama
to Obama lean
Massachusettsfrom Strong Obama
to Obama lean
Nevadafrom Toss Up McCainto Toss Up Obama
New Mexicofrom Obama leanto Toss Up Obama
North Carolinafrom McCain lean
to Toss Up McCain
Ohiofrom Toss Up McCain
to Toss Up Obama
South Carolinafrom McCain leanto Strong McCain
Texasfrom Strong McCainto McCain lean
Washingtonfrom Obama lean
to Strong Obama
Wisconsinfrom Obama leanto Toss Up Obama
*Weighted Average within a fraction of a point of changing categories.

And the Watch List? Virginia will be back on the list tomorrow -- with the Zogby polling included -- but without the Zogby date, the Old Dominion would be back off the list. Ohio is very close to sliding off the list without those polls as well. Georgia will come off the list tomorrow with or without these polls and South Carolina is slightly safer for McCain with that 1 point Obama lead in their June poll dropped from consideration. Finally, Massachusetts reenters the list as well after a prolonged absence. Well, the Bay state would be back on if the Zogby poll there weren't propping the state's average up to some degree.

In the end, the biggest surprise was that South Carolina didn't shift into safer McCain territory. North Carolina's shift was expected, but even that move was muted. The lesson here is that, yeah, Zogby adds some noise, but the overall effect is not that severe. Should we keep them, should we drop them? That, my friends, is certainly up for discussion.


Recent Posts:
The Electoral College Map (9/22/08)

Today's Agenda

The Electoral College Map (9/21/08)

Monday, September 8, 2008

2008 vs. 2004: Glass is Half Empty/Glass is Half Full

If you're like I've been today, you've been clicking refresh every so often over at Pollster to see if any new state-level polls have emerged in this post-convention period. [There were several late-day releases, but I'll get to that in a bit when I post the first of the daily electoral college updates. I think we'll have enough polling volume that we'll be able to pull it off. At the end of the election, we'll have a much richer picture of what was happening over these last fifty-seven days.] It is one thing to answer the "convention bounce" question with national polls, but I've always been inclined to discover how this is working out on the state level. Is that national bounce that we've witnessed for McCain uniformly distributed across all states, or is it the case that McCain/Palin just fired up partisans in already-red states with their convention last week? I suspect the answer is somewhere in the middle, but I'd like to take an opportunity to cast an eye to the past for a guide in all this. As you'll recall, about a month ago, I examined how, using FHQ methodology, 2004 would have looked at the same, mid-August point of the campaign. The middle of August in 2004 was roughly two weeks after the conclusion of the Democratic convention, so we would expect to have seen Kerry in a somewhat advantageous position in the electoral college projection relative to Bush. And that's exactly what we saw. Kerry had essentially the same projected lead in the electoral college that Obama held in the same mid-August period.

However, given that mid-August was in the time after Kerry's convention, we'd expect to see a bounce for him as well, right? Well, since Kerry got basically no bounce (see the graph and point D04) out of his convention that isn't necessarily the case. The Massachusetts senator didn't get anything out of the convention in the national polls, but did he in the state polls? The thing that marked 2004 was the tight equilibrium that we saw across much of the campaign cycle. The Democratic convention didn't do anything to shake up the steady state of the race. In fact, as you'll see below, that state was held through and even past the Republican convention in 2004. September 8, 2004 was roughly a week after the conclusion of the GOP's convention and at that point there had not been any change to the distribution in the electoral college. Kerry, then, didn't get a bounce out of his convention, nor does it appear that he was hurt in any way by the modest bounce Bush received from his convention -- at least not in the week following the conclusion of the Republican convention.
[Click Map to Enlarge]

After the conventions then, Kerry still held just enough of an advantage in enough states to provide him with a 44 electoral vote edge over the incumbent president. But as I'm sure President Kerry will attest, that lead did not last. While the margin stayed the same the fundamentals of the race were changing. The states that shifted over the last 100 days of the race had begun, in most cases, their moves toward President Bush. New Mexico shifted from a Kerry lean to a toss up favoring Kerry. And though Florida continued to ever so slightly favor Kerry, the Sunshine state was basically a tie and was slowing inching toward the Republican nominee. The only other state that shifted sides was Iowa and the Hawkeye state actually moved slightly toward Kerry in the mid-August to early September period in 2004. Still, the lead was under three points and Bush was obviously able to swing just enough votes to pull out a victory in the state in November.

Colorado was also an interesting case over this period. The Centennial state, like Iowa, moved toward Kerry over this period, in the process shifting from an Bush lean to a toss up state. Why is that interesting? Well, obviously the trend is counter to what we might expect of a Bush state in the post-convention period, but Colorado also had a special measure on the ballot that fall. The measure, if supported by voters, would have distributed the state's electoral votes by congressional district in the manner that Maine and Nebraska do and would have taken effect for the 2004 electoral college session in Washington in December following the election. The measure was voted down, but in the context of this tightening, is an interesting footnote to the election.

So how does this enhance our understanding of what is happening in the current race for the White House. For that let's start by comparing the map above to the map from yesterday's electoral college projection update.
[Click Map to Enlarge]

There is quite a bit of overlap between the toss up states in each cycle. But 2008 has brought several atypical states into the mix. Indiana, Montana, North Carolina and North Dakota are all much closer than they were just four years ago. All still favor the Republican candidate, but are closer. States like Iowa, Minnesota, Oregon and Wisconsin that were toss ups four years ago are all leaning more heavily toward the Democrat in 2008. That has helped to provide Obama with a cushion that neither Kerry nor Gore enjoyed in either of the last two elections. Obama is ahead and doesn't need Florida to cross the 270 electoral vote threshold. And though the Illinois senator is slightly ahead in Ohio as of now, he could cede the Buckeye state to McCain and still eke out an eight electoral vote victory assuming McCain also inches ahead in currently tied Nevada. In fairness, we don't have even a partial picture of how the conventions are playing on the state level. [Well, we do now, but I'll get to that in a little while.]

The Electoral College Spectrum*
MA-12
(15)**
HI-4
(168)
WI-10
(264/284)
NC-15
(167)
KS-6
(45)
RI-4
(19)
WA-11
(179)
FL-27***
(291/274)
AZ-10
(152)
AK-3
(39)
NY-31
(50)
ME-4
(183)
NV-5
(296/247)
SC-8
(142)
OK-7
(36)
CT-7
(57)
MN-10
(193/355)
OH-20
(316/242)
GA-15
(134)
MT-3
(29)
VT-3
(60)
NM-5
(198/345)
MO-11
(327/222)
SD-3
(119)
ND-3
(26)
IL-21
(81)
OR-7
(205/340)
AR-6
(333/211)
LA-9
(116)
NE-5
(23)
MD-10
(91)
MI-17
(222/333)
WV-5
(338/205)
KY-8
(107)
ID-4
(18)
CA-55
(146)
NH-4
(226/316)
CO-9
(347/200)
IN-11
(99)
MS-6
(14)
NJ-15
(161)
IA-7
(233/312)
VA-13
(360/191)
AL-9
(88)
WY-3
(8)
DE-3
(164)
PA-21
(254/305)
TN-11
(178)
TX-34
(79)
UT-5
(5)
*Follow the link for a detailed explanation on how to read the Electoral College Spectrum.
**The numbers in the parentheses refer to the number of electoral votes a candidate would have if he won all the states ranked prior to that state. If, for example, Bush won all the states up to and including New Hampshire (all Kerry's toss up states, but Michigan), he would have 323 electoral votes. Both candidates numbers are only totaled through their rival's toss up states. In those cases, Kerry's number is on the left and Bush's is on the right in italics.

***Florida is the state where Kerry crosses (or Bush would cross) the 270 electoral vote threshold to win the presidential election. That state is referred to as the victory line
.

Both the Electoral College Spectrum and the Watch List of this period in 2004 underscore the precarious position in which Senator Kerry was at the time. His hold on Florida was the only thing keeping him above 270 and then it was only by a fraction. Plus the number of light blue toss up states had snaked all the way into the the second column of Kerry states. This was compounded by the fact that all the states that were near moving -- those on the Watch List below -- were predominantly Kerry states. And while many were on the line between toss up and lean, most had already moved into the toss up category and would end up staying there or in the case of Iowa and New Mexico, would move into Bush's column.

The Watch List*
StateSwitch
Californiafrom Strong Kerryto Kerry lean
Floridafrom Toss Up Kerry
to Toss Up Bush
Mainefrom Kerry leanto Toss Up Kerry
Marylandfrom Strong Kerryto Kerry lean
Michiganfrom Toss Up Kerryto Kerry lean
Minnesotafrom Toss Up Kerryto Kerry lean
Nevadafrom Toss Up Bush
to Toss Up Kerry
New Hampshire
from Toss Up Kerryto Kerry lean
New Mexicofrom Toss Up Kerryto Kerry lean
Oregonfrom Toss Up Kerryto Kerry lean
Tennessee
from Bush lean
to Toss Up Bush
*Weighted Average within a fraction of a point of changing categories.

So, glass is half empty, Obama is in the same position Kerry was in (in terms of an aggregation of electoral votes). But, glass is half full, Obama has built-in advantages that neither Kerry nor Gore before him held in their respective runs for the White House. Where the 2008 race stands now, though, depends on how these states begin breaking with the information the conventions of the last two weeks have added to the discussion.

We'll get to those shortly.


Recent Posts:
The Electoral College Map (9/7/08)

On to the Debates! -- And a Note on Compression

Presidential Primary Reform: Still Alive with the GOP?