Princeton Election Consortium

A first draft of electoral history. Since 2004

Are Americans really jingoistic yahoos? A cautionary statistical tale

April 13th, 2014, 9:36am by Sam Wang

It can be good for a laugh to view U.S. citizens as people who don’t have a clear idea of what’s happening outside their borders…but still want to launch a military attack. This week in The Monkey Cage comes a finding that feeds that view. The headline is impressive: “The less Americans know about Ukraine’s location, the more they want U.S. to intervene.”

But how big is the reported effect, and what does it really say about American attitudes? [Read more →]

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Autism NYT piece: Postscript

April 6th, 2014, 7:00am by Sam Wang

I’ve received some useful feedback on the NYT piece on autism. I have extra notes to offer on three topics: (1) elective induction, (2) environmental toxins, including endocrine disruptors, and (3) the lack of a true link with SSRI use. [Read more →]

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How to think about autism risks

March 29th, 2014, 8:57pm by Sam Wang

For those of you coming here from the NYT, welcome! If you’re interested in drilling into the scientific literature, I’ve archived some articles here. Note: if you’re having trouble getting the links from the NYT piece to work, the link above has all the correct files. Basically the NYT site messed up the “~” character in the URL. Soon I’ll document the calculations behind the risk ratios.

In my article in the Sunday New York Times on how to think about autism risks, I apply meta-analytical techniques to autism research literature. It’s nearly impossible to get a good overall perspective from news reports. However, I provide a way to look at it all at once. My secret decoder ring takes the form of risk ratios. Check it out.

As stated in the article, by far the largest risk is genetic. In comparison, the measured impact of environmental risks ranges from nonexistent to small, unless you work directly with chemicals in a factory. The small risks might actually be due to stress. For more information, check back later – or see PubMed, which allows you to search the vast research literature on autism.

You can read about my own neuroscience research here.

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Lou Reed, 1942-2013: Shut the door!

October 27th, 2013, 7:43pm by Sam Wang

The Velvet Underground was one of the first really interesting bands I listened to. They are simple, but amazing. I learned about them around 1982 in an interview with R.E.M., who revered them. Also, my house at Caltech had a rock band composed entirely of physics majors, who only did V.U. covers. This was within their skill set.

Founder Lou Reed was a monument. He had a liver transplant in May. Today the news comes that he has died. He leaves behind the equally interesting performance artist and composer Laurie Anderson, who he married in 2008.

You may know other songs. Here is one I liked quite a lot, partly because of the background chatter. Shut the door!

Update: the embedded ad is for “Weaning off Percocet.” That’s perfect.

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Just how steep is that climb in 2014, anyway?

October 24th, 2013, 10:52pm by Sam Wang

With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.

-John von Neumann

If we want to forecast House control in 2014 without drilling into individual Congressional districts, we need to know two things:

  1. What national popular vote margin is needed to flip House control; and
  2. What the likely range for the national popular vote margin will be.

For #1, last week here at PEC I estimated that a margin of D+4% to D+5% (i.e. Democrats win popular vote by 4-5%) would be necessary. My estimate is not far from other analysts.

However, a notable outlier is Alan Abramowitz at the Crystal Ball, who claims D+13% is needed. This appears to be an error of overfitting, which I have previously mentioned in relation to The Monkey Cage* and FiveThirtyEight. That is not bad company…but seeing as how this problem is a recurring one, I would like to get into the details. It might reduce the possibility of similar future missteps. [Read more →]

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How high is the House levee?

October 17th, 2013, 7:33pm by Sam Wang

Today we have some outlier statements made by other political analysts. As rounded up by Andrew Sullivan, we have Nate Cohn at the New Republic quoting Alan Abramowitz:

Democrats need a 13 point Democratic edge on September 1 to win the 17 seats necessary to retake the chamber in November.

For any wave election, that would be a very soundly built levee. However, recent data suggest this statement is rather overstated, for two reasons:

  1. In the last 6 elections, the drift from previous-year generic-opinion polls to November outcomes is a median of 3 points (4.6 points for midterms only).
  2. Republican-favoring gerrymandered districts are weaker than they look. Because they seem to have more independents than other Republican districts, the necessary national popular-vote margin for a Democratic takeover is lower than in 2012, and I estimate it at about 4 points.

I have analyzed this all recently. I think the levee could be breached by a 7-point generic polling margin next October. Also, here’s a rather good overview by David Wasserman at the  Cook Political Report. Let me review a few points about what appears to be in past and present polls. [Read more →]

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How long will the shutdown’s effect on opinion last?

October 17th, 2013, 10:42am by Sam Wang

A video clip of my appearance last weekend on MSNBC is here. It is brief, but I did state the main point: the shutdown leveled the House playing field in a rather unexpected manner. Republican-gerrymandered districts (FL, MI, OH, NC, PA, VA, WI) have swung away from Republicans about twice as hard as the rest of the nation. Why? When you pack your opponents into a few districts, your own districts end up with a lot of independents, who are swayable.

My own analysis of current surveys indicates that in a Congressional election today, Democrats would retake the House with >90% probability and a 50-seat margin. Last week I pointed out that assuming historical patterns, by next November that probability for the actual election diminishes to 50% or less. Another estimate gives a comparable probability of 25-35%.

However, the last two weeks have been quite strange – as evidenced by the fact that you are visiting the Princeton Election Consortium, reading about polls an entire year before a midterm election! So something might be different. I’ve never seen such a rapid and large shift in the generic Congressional preference. Will this “shutdown bounce” last? Or will it dissipate quickly?

I estimate that in the absence of any further political crisis events, the current bounce will affect opinion for between 2 and 6 months. Here’s the argument. [Read more →]

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A difference with Nate Silver? Not exactly.

October 12th, 2013, 3:30pm by Sam Wang

From Brad DeLong, this headline caught my attention:


Always good to see the Ali-Foreman thing.

Seriously, though, take a look at Silver’s essay at his new home at Grantland. His description of conditions is a good overview of pre-shutdown conditions. If we stop with the continual budget crises, then I agree that we might drift back toward the conventional prediction (R’s keep control in 2014).

Where we differ is that I am adding to that picture the sea change in the last two weeks. As I’ve written, there’s big stuff going on. Poll movement is substantial and rapid in the generic Congressional ballot. Multiple polls, including a detailed one from NBC/WSJ, show that public sentiment has turned against the GOP. Under the radar, gerrymandered districts are swinging much harder than I was expecting. If the election were today, Democrats would control the House by about 50 seats. That will fade, but by how much?

Silver lists other events that didn’t move opinion: Benghazi, and the IRS business, and Syria. But the shutdown has, bigtime. I agree with him that most pundits emit bulls**t, which is why I am working on a prediction model. Right now, the model is saying: as long as the GOP stays on its current path, where the House goes next fall is an even-money bet.

→ 19 CommentsTags: 2014 Election · House

Has the shutdown leveled the House playing field?

October 11th, 2013, 10:08pm by Sam Wang

Tomorrow at 4:00pm ET, I’ll be on MSNBC’s Disrupt with host Karen Finney and E.J. Dionne. In addition to the sharp swing in the last week (now a median of D+8% in the generic Congressional, n=5 surveys), I’ll mention this:

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→ 13 CommentsTags: 2012 Election · 2014 Election · House

What the Gerrymander giveth with one hand: House control in 2014 now a toss-up

October 10th, 2013, 10:30am by Sam Wang

Andrew Sullivan has collected some commentary that argues against my suggestion that the House could potentially flip in 2014. There were some good points made. However, it should be noted that some of these analysts’ comments have been OBE (Overtaken By Events) – the shutdown. The incredible numbers in yesterday’s NBC/WSJ poll pretty much demonstrate that point: approval of the Republican party is at an all-time low…and 60% of voters would vote out every single member of Congress at once including their own if given the chance.

All of the arguments on this subject can and should be quantified. It’s just like last year’s Presidential race: is any of this punditry data-based? Today I start to outline a true prediction. I give a “toy model,” i.e. step 1 toward something more realistic. The toy model relies on a prediction of popular vote only. At the end, I start to add a little bit of complication. I invite you to add more complication in comments.

Provisionally, it looks like the following: In a little over a week, the shutdown has increased the probability of a Democratic House takeover in 2014 from 13% to as high as 50%.

The first number (13%) is is exactly as expected if House trends were following expectations from analysts’ conventional wisdom and political science research. But the shutdown, combined with the fluidity of gerrymandered districts, has added a highly unexpected twist. The 50% figure could swing back toward the Republicans, or it could go further toward the Democrats. For certain, it gives a measure of an unusually fast change in the national mood. Let’s dive in.

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→ 16 CommentsTags: 2014 Election · House