Obvious Poll Trends and The Media

As Obama and Hillary move their campaigns into the final week before the Pennsylvania primary, it's useful to examine some past polling phenomenons. If you look at the tracking poll averages from just about every highly contested state to date, you'll notice strikingly similar trends.

Here's Iowa:

And New Hampshire:

And Texas:

And Ohio:

These graphs all show a similar pattern. While the spreads between Obama and Clinton a few weeks or months out were relatively large - 20 to 30 points in some states - as the campaigns headed into election day, the spreads universally shrank.

Now take a look at Pennsylvania's trends:

Again we see the same shape we've been seeing in state after state. So what's happening here?

First, the obvious. As it gets closer to voting day in these states, the two campaigns spend more time and money there and opinions change. But I think the real dynamics lie a bit deeper.

As voting day approaches, people think more deeply about their choices. While someone might have supported a candidate earlier in the race simply because that candidate had higher name recognition or a voter happened to catch one of their speeches on television, when finally forced to make a real choice, voters switch support. Most support in the early stages of the primary in each of these states was "soft" support, based on little information or contact with the campaigns. As people actually begin to make up their minds and move from "soft" support to "hard" support, there is a lot of churn in the poll numbers.

While this idea is fairly obvious, media coverage and general discussion around these primaries has tended to ignore these trends. For example, headlines like "Polls: Obama gains on Clinton in Pa." are extremely misleading. Obama isn't really "gaining" support - if by gaining support you mean convincing Clinton supporters to vote for Obama. Instead, the information people are giving pollsters months before the election is misleading. "Soft" supporters along with independents are likely telling pollsters who they support without much thought. As the race gets down to the wire, people actually sit down and make up their minds.

(As a side note, I would say the same thing is happening with McCain's recentsurge in the polls. With Democratic voters split between Clinton and Obama, McCain has seen a surge that will likely evaporate once the general election race gets started in earnest.)

This is not to say, of course, that campaigns don't matter. If you look closely at the above graphs, you'll notice Hillary Clinton almost always experiences an uptick in polling towards the end of the race in each state, even if her general trend was downward. Clearly, events that happen on the campaign trail are having an effect on voters.

Of course, both campaigns are rightly trying to play the expectations game with these numbers, but we keep falling for it. This trend is happening in every single state every single time. As voting day approaches, the polling narrows. Why are we still surprised at this phenomenon? And why do most media outlets think this is still news?

The views expressed by J Ro are his and his alone.

Tags: 2008 election, Barack Obama, Hillary Clinton, Pennsylvania Primary (all tags)

Comments

36 Comments

Re: Obvious Poll Trends and The Media

I don't know how to embed images, but if you look at this compilation of PA data, you get a very different view of opinion trends. http://www.pollster.com/08-PA-Dem-Pres-P rimary.php

by politicsmatters 2008-04-13 05:09PM | 0 recs
Re: Obvious Poll Trends and The Media

I've got those image from Real Clear Politics, but this aggregation, though slightly different, still seems to exhibit the same trends of polls narrowing as the primary approaches. What are you seeing that's different?

by J Ro 2008-04-13 05:20PM | 0 recs
Re: Obvious Poll Trends and The Media

All I'm saying is that realclear politics and pollster use different ways of plotting the data and because of that, the graphic representation of the data looks very different.

I'm not sure why that happens, except that pollster uses fairly sophisticated methods that are designed to locate trends. They place specific polls in relation to other polls, I believe, for the date when the poll was finished. Then they can plot the line through the set of completed polls.

realclearpolitics does averages at particular points in time, but I've never been able to figure out if they have a rule about what polls are included in any particular period.  

by politicsmatters 2008-04-13 05:33PM | 0 recs
Re: Obvious Poll Trends and The Media

Keep in mind that realclearpolitics is a news site primarily and it's run by people who have a background as campaign consultants and reporters.

On the other hand, pollster.com is run by people with PhD level training in statistics and public opinion polling, so they are more sophisticated in the methods they use.

Don't get me wrong -- Realclearpolitics has its advantages. It's good at posting polls quickly. But figuring out how best to graphically present data AND in particular how best to track trends, that's not their strong suit.  

And pollster has a good blog http://www.pollster.com/blogs/ and there's a nice blog by one of its principals http://politicalarithmetik.blogspot.com/

by politicsmatters 2008-04-13 05:39PM | 0 recs
Re: Obvious Poll Trends and The Media

Thanks for that differentiation. I'll definitely keep pollster more on my radar in the future.

by J Ro 2008-04-13 05:51PM | 0 recs
Re: Obvious Poll Trends and The Media

My impression is that pollster.com comes out with a more conservative line because because outliers are weighted far less than those closer to the midpoint. So the dots that are farther away from the line (polls that look really great for one candidate) count less than the ones closer to it (polls that more closely resemble other polls).

The long and the short of it is that both kinds of plots should be looked at with the understanding that pollster.com gives a more conservative picture of the candidates' movement.

by davefordemocracy 2008-04-14 05:44AM | 0 recs
Re: Obvious Poll Trends and The Media

Not to get too technical, but that's because pollster.com plots their line using regression* as a method. It is not just a set of averages which can get thrown off by outliers; plus, as I mentioned, it's never clear which polls, gathered from what period of time, show up in any particular average.  From what I can tell, the average presented by realclearpolitics can be polls gathered over three days or over a week. That really undermines the validity of their presentation.

* regression - http://en.wikipedia.org/wiki/Regression_ analysis

by politicsmatters 2008-04-14 05:53AM | 0 recs
Re: Obvious Poll Trends and The Media

And while sometimes the graphical representation of data on pollster seems more conservative in capturing trends, right now they show more pronounced movement for Obama in PA.  Of course, who knows if that will last, but there is a clear difference in the pictured data trend.

by politicsmatters 2008-04-14 05:55AM | 0 recs
Re: American Research Poll has Hillary UP 20pts

Obama's momma!  That's hilarious!  You owe me a new keeboard!  LOL!

(Pause)

Or you could say that a poll that has a 20 point swing in the course of a week raises methodological and procedural questions.

(Pause)

Or you can wait a week for the poll on the 22nd.  

by LarsThorwald 2008-04-14 07:27AM | 0 recs
Re: Obvious Poll Trends and The Media

Thank you for putting the current situation into a broader perspective. It will be even more instructive to add NC and Indiana on 4/27.

by pan230oh 2008-04-13 05:28PM | 0 recs
Re: Obvious Poll Trends and The Media

Thank you for this analysis. We need more of it on MyDD.

:o)

by Veteran75 2008-04-13 05:33PM | 0 recs
Re: Yo, Amigo -

You missed something.

In almost every graph shown, there is a Clinton uptick in the week preceding the primary.

Also, you have two different time scales represented in the graphs -
One year in the first two - one month in the second two.
That gives this an apples/oranges quality.

by johnnygunn 2008-04-13 05:35PM | 0 recs
Re: Yo, Amigo -

I did mention that uptick, but only barely because honestly, I'm not sure why it happens. All I can say really is that campaigns matter, and what the politicians do at the end of the campaigns matters. But I can't really put a good reason on it.

by J Ro 2008-04-13 05:50PM | 0 recs
Re: Yo, Amigo -
Indeed, you did -
And I missed it - sorry.
by johnnygunn 2008-04-13 05:53PM | 0 recs
Re: Yo, Amigo -

Why the uptick?

Could it be that a segment of people who are ambivalent towards Clinton finally decide that Clinton is preferable for the reasons she puts forth?  Experience & Policy. They are not thrilled with her, but find her a slightly better choice.

I'll call them "Hardened Progressives" -
The kind who put a clothespin on their noses.

by johnnygunn 2008-04-13 05:57PM | 0 recs
Re: Yo, Amigo -

Ugh, you just got rid of Mark Penn (the reason you are losing) please don't create "pennisms" when you finally culled the cancer.

by kasjogren 2008-04-13 06:56PM | 0 recs
yes yes

"Hardened Progressive".

Not real progressives... no, no..you have to attach an epithet to it an put it in quotes.

How Mark Penn of you.

by kindthoughts 2008-04-13 07:23PM | 0 recs
Re: Yo, Amigo -

yeah, it's impossible to know exactly why that happens but it only happens in states where Clinton had been leading big. In states that Obama is expected to win, that uptick does not occur right?

that's worth exploring if true.

so, if it is true that that uptick only occurs in states where Hillary leads big, it leads me to think that the main reasoning is people who have initially supported Hillary begin to question her viability and look to Obama as a good alternative. However, after some campaigning and negative television calling Obama out on his lack of experience, or other issues, these very same people begin to question Obama's viability and go back home to their initial choice.

it's not surprising IMO and it's something I've come to expect ever since NV. What I find more interesting (and difficult) is trying to figure out by how much Obama over performs in states friendly to him. Those numbers have mostly all been staggering.

by alex100 2008-04-14 04:55AM | 0 recs
Re: Yo, Amigo -

I haven't looked in depth, but it does seem that there is narrowing of polls even in states where Obama has won by big margins. It's worth a deeper exploration, though.

by J Ro 2008-04-14 10:14AM | 0 recs
A-B-C ... Line!

D. But of course!  Thank goodness for blogs.

I think 99% of the readership is already familiar with the notion of late-deciding voters.

Why does the media report on state of the race?  Ah... because that is the function of the media?

by Quicklund 2008-04-13 05:50PM | 0 recs
Re: Obvious Poll Trends and The Media

Circular reasoning. You use the line "If you look at the tracking poll averages from just about every highly contested state". Of course, a state is only considered "highly contested" if the polls there are close. So yes, in states where polling numbers are close before the primary, the polls tend to have closed in the weeks preceding it. O RLY?

This obviously doesn't happen in states where Obama leads, because they tend to be blowouts. So they don't qualify as highly contested. So "polls tightening" has happened in about fifteen contests to date.

by BlacknBlue 2008-04-13 05:50PM | 0 recs
Re: Obvious Poll Trends and The Media

Well, only kind of circular logic. I mean, yes, there is that element to this analysis, but also campaigns tend to spend more time and money in these states, which effects the polling too. So it's more than just a circle...

by J Ro 2008-04-13 05:53PM | 0 recs
Re: Obvious Poll Trends and The Media

OT - but I just saw an ad for "Expelled" (the insane pro-intelligent design movie by Ben Stein) on the MYDD main page.

Take it away!!!! lol

by belili 2008-04-13 05:53PM | 0 recs
Re: Obvious Poll Trends and The Media

This "should" be obvious but isn't.  Nice entry.  I still think that a 5-9 point win by Hillary is what I would call, even when she was "up" by 20.  All supporter spin aside the only race that actually surprised me with the final tally was Ohio.

by kasjogren 2008-04-13 06:51PM | 0 recs
Re: Obvious Poll Trends and The Media

After seeing these charts I find it hard to discern how Clinton supporters can suggest that the outcome in FL would have been as lopsided in her favor if both had been allowed to fully campaign.

by DreamsOfABlueNation 2008-04-13 08:16PM | 0 recs
Re: Obvious Poll Trends and The Media

I'm not sure I understand your thesis.  I'm going to paraphrase and if I'm wrong please correct me: When the Senators Obama and Clinton go head to head in contested states, Obama always closes moving towards the election, so it is inappropriate to label him as closing in the polls.

I'm not sure I understand.  What am I missing?

by such sweet thunder 2008-04-13 09:05PM | 0 recs
Re: Obvious Poll Trends and The Media

i had this same reaction.

He lost me at the "gaining support" part. The reasoning that "gaining support" can only be done by gaining Clinton supporters isn't necessarily true. You can gain in the polls by just pulling in a majority of the undecideds.

and if a person is soft for Hillary but switches to Obama, that's considered a "gain" in my book.

by alex100 2008-04-14 05:02AM | 0 recs
Re: Obvious Poll Trends and The Media

This is more of a media critique than anything else. The headlines we see from poll analysis always makes things out to be more dramatic than they are. If this phenomenon happens every time, headlines like "As polls narrow, candidates fight for votes" are more appropriate than "Obama gains a point on Hillary!!!11!"

by J Ro 2008-04-14 10:15AM | 0 recs
Re: Obvious Poll Trends and The Media

I agree with such sweet thunder. The case would be much more convincing if you could show some cases in which Obama started of with a strong lead a year ago or a month ago, and then Clinton pulled even with him or slightly ahead of him during the run up to the election. Without any cases like that, it certainly looks like what happens is that if Obama is behind, he steadily gains ground, but if Clinton is behind she doesn't. Somehow, that seems like it may be connected to campaigning. Merely because something happens over and over again in races between two specific candidates, does not mean it has nothing to do with those specific candidates.

Alternatively, showing some polls from previous elections in which the anointed candidate starts out strong, but steadily loses ground to an insurgent candidate in primary after primary, would help to show that the phenomenon is related to low info polling far ahead of the election.

What you have now supports "Obama is an awesome campaigner, and Clinton is good at the closing" much more than it supports "Whoever is ahead to start off with loses that lead as the election gets closer."

by alephnul 2008-04-14 02:27AM | 0 recs
Re: Obvious Poll Trends and The Media

you make a good point.

I'm in my graduate thesis at Yale and much of my work deals with how to parse out data. It's quite obvious that the data someone picks is chosen to paint a certain story. So there's a moral judgment being made in one form or another.

From this data, we're forced to deal with a certain "truth" but what about what isn't told? There's a heavy amount of polling information being left out of these examples which would support a different conclusion. Tufte calls this the "lie factor" and judging by how the information is presented, the "lie factor" in this example can be considered rather high.

There certainly seems to be a reason why the thread starter cherry picked this data over a wider range of data that would not support his conclusion. And that's fine in a forum like this one because as we've seen, posters are allowed to chime in about how this incomplete data paints an incomplete picture.

by alex100 2008-04-14 05:18AM | 0 recs
Re: Obvious Poll Trends and The Media

alex100 - I'm a big admirer of Tufte's work on the visual presentation of data.  Thanks for chiming in!

by politicsmatters 2008-04-14 05:57AM | 0 recs
Re: Obvious Poll Trends and The Media

I may do a deeper analysis, but honestly, I'm not a huge numbers guy, so I'll quickly be out of my depth. Plus, the heavily contested states are more heavily polled, making finding reliable data easier. But yeah, other states should be explored.

by J Ro 2008-04-14 10:17AM | 0 recs
Re: Obvious Poll Trends and The Media

isn't gaining support??? Are you kidding me.

Yes, he is.  plain in simple.  We might not like it but he is; he always does.  That is why he is winning.

and, since we've all been saying Obama has been speaking condescendingly, i thought i'd balance it out. but i assume, nobody here will think much of it.

http://www.youtube.com/watch?v=rulSnAM6g mM

by wickedmessenger 2008-04-14 05:34AM | 0 recs
Re: Obvious Poll Trends and The Media


Data mining anyone???

-

by wickedmessenger 2008-04-14 05:35AM | 0 recs
Media Desperate To Keep Hillary Afloat

Oh no, if Obama runs away with this they have to develop new story lines and do a couple days of actual work. Hillary and the media are both desperately trying to make her lazy "maccaca" strategy fly.

Why isn't it working?  Let's see if her campaign degenerates into internal screaming matches again.

by bernardpliers 2008-04-14 06:46AM | 0 recs
Re: Obvious Poll Trends and The Media

Another great polling site http://www.fivethirtyeight.com/

by politicsmatters 2008-04-14 08:18AM | 0 recs

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