betting markets react to Abbott’s win

Monday November 30, 2009

Filed under: Australian Politics — jackman @ 9:42 pm

In the wake of this morning’s events in Canberra, Centrebet’s price on Labor has come into 1.14 to the Coalition’s 5.15 (implied probability of Labor win is .82).

As of 9am (the start of the FPLP meeting) the prices were 1.16 to 4.75 (.80).

On Nov 1: 1.24 to 3.90 (.76).

Oct 1: 1.27 to 3.60 (.74).

Sep 1: 1.33 to 3.20 (.71).

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Galaxy Poll on Insiders

Sunday November 29, 2009

Filed under: Australian Politics,statistics — jackman @ 10:07 am

(Mock?) outrage on the ABS’s Insiders program that a Galaxy poll had been “weighted and projected” to be representative of the Australian population. The noted scientist/statistician Andrew Bolt took great umbrage at this, describing it as “dodgy” as the evidence for anthropogenic global warming; that didn’t stop Bolt from going on to use the poll’s findings to support his criticism of Turnbull.

Andrew & Co: get over it. All polls are weighted (although I’m not sure what “projected” means in this context, maybe to get coverage of non-sampled areas?). The one interesting factor here is the small sample size, which after weighting results in an effective sample surely much smaller than 400.

On the substance, I’d note that while much is made of differences between ALP and Coalition voters on climate change issues (as I did in my work for the USSC), at no point in Glenn Milne’s writeup of the poll is the actual ALP/Coalition vote split reported. That is, the problem isn’t so much that Coalition voters look different from Labor voters or the population at large, but the fact that Coalition voters are so comprehensively outnumbered by Labor voters in virtually every recent poll of the Australian electorate (and that one way to boost Coalition vote share might be to support the ETS).


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Australian election betting markets

Thursday November 26, 2009

Filed under: Australian Politics — jackman @ 2:38 pm

And unsurprisingly, a fair amount of movement in the betting markets. The Centrebet prices as of this morning (Sydney time) correspond to an 80% chance that Labor wins the next election. That is up from about 68% as recently as late August.

Screen Shot 2009-11-26 At 2.37.23 Pm

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climate change (wedging the Liberals)

Filed under: Australian Politics — jackman @ 9:38 am

A few observations on the climate change issue currently wrecking havoc in Australian politics.

The following table comes from a report I did for the United States Studies Centre at the University of Sydney; a link and discussion appears below the fold.

Screen Shot 2009-11-26 At 12.24.31 Pm

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mprobit in Stata is…

Thursday November 19, 2009

Filed under: computing,statistics — jackman @ 4:47 pm

Not what you might think.

Take the MNL model (with IIA etc) and add a probit link. It is odd that they would call that multinomial probit. Most people would understand “multinomial probit” as a model for multinomial outcomes with multivariate normal disturbances (in general, with non-zero covariances). A screen full into the documentation for Stata’s mprobit it says:

The error terms are assumed to be independent, standard normal, random variables. See [R] asmprobit for the case where the latent-variable errors are correlated or heteroskedastic and you have alternative-specific variables.

A trap for the hasty, the unwary…?

This said, the “real” multinomial probit function in Stata uses some funky options for controlling he nasty integrations necessary to evaluate the likelihood for this model (i.e., simulated MLE a la GHK, with an option for Halton sequences to drive the quasi-Monte Carlo integration). It would be fun to play with this Stata function, alongside the fully Bayesian/MCMC implementations in R for this model (e.g., MNP and bayesm).

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Saturday November 14, 2009

Filed under: computing,statistics,type — jackman @ 1:54 am

A recent e-mail correspondent writes:

I have a degree in applied statistics, and I’m really interested in the lectures notes you put on your website about Bayesian approaches and simulations. That’s something i need to discover and it looks really rich and interesting. I also use R on a very regular basis.

The purpose of this email is that I’m using LaTeX to write some documents, and i can’t find anything on how to install the FF Meta police, which is very clear and easy to read.
Have you anything about that by any chance?

First of all, I should take the Bayes notes down and point you in the direction of The Book (done!).

On FFMeta, I don’t quite get the references to “FF Meta police”. But here is how I did it (below the fold).

Screen Shot 2009-11-14 At 1.10.52 Am

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Stupak amendment

Monday November 9, 2009

Filed under: politics,statistics — jackman @ 2:27 am

Some graphs looking at the voting on the Stupak amendment. This roll call sliced up the Democrats pretty nicely. Thumbnails below link to PDFs. Democrats only in the 1st graph, looking at the relationship between the Ayes and Noes and Obama vote share in the representatives’ respective districts.

Stupakobamavote-1 Stupakbyidealpoint-1 Stupakvertical-1

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House vote, Health Care, by ideal point

Sunday November 8, 2009

Filed under: politics,statistics — jackman @ 5:11 pm

And one more look at last night’s vote, this time with each representative’s estimated ideal point (based on the entire 111th House thus far) as the predictor, similar to what I did for the Coburn amendment in the Senate.


Update: and yet another graphical rendering (click on the thumbnail for the PDF).


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Democratic split on Health Care final passage

Filed under: politics,statistics — jackman @ 1:45 am

Here is a quick look at how Democrats split on the House vote on the Affordable Health Care for America Act, as a (logistic) function of Obama vote in their district.


Davis (AL-7) and Kucinch (OH-10) are the big “errors” among the “Noe” votes; Kucinch had been telegraphing his opposition to a too meek reform bill for some time. Davis is the same boat (“is this the best we can do?“).

Marion Berry (AR-1) is the biggest “error” among the “Aye” votes; he voted yes while representing an Arkansas district where McCain got 59% of the vote and Obama just 38% (but, perhaps reflecting much about that part of Arkansas, he was unopposed in the 2008 Congressional elections) and he seems to have long history of being in the forefront of Democratic reform efforts on health care.

Update: a nice take on the Dems voting Noe from the NYTimes.

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Coburn amendment redux; political science lobbying?

Saturday November 7, 2009

Filed under: politics,statistics — jackman @ 4:26 pm

I did a little work on the Coburn amendment rollcall. The vanilla spatial voting model fits the roll call reasonably well; I use all 341 roll calls cast by the 111th U.S. Senate (at least as of this morning when I ran the analysis) to estimate the ideal points, and then look at the fit to the roll call on the Coburn amendment.

The graph (thumbnail below) summarizes the fit, with the curve tracing out the predicted probabilities as a function of estimated ideal point (these come a simple probit regression of the actual votes on the ideal points). The estimated cutpoint — the point where a legislator is indifferent, on average — is between the ideal points of Voinovich (R OH) and Murkowski (R AK).

The “surprises” (or deviations from “pure” spatial voting) are show on the graph:

Snowe (R ME) and Collins (R ME) are to the left of the cutpoint and voted in accordance with the model prediction.

Bayh is up for re-election in 2010, as is Voinovich; for what it is worth, both are in Midwestern states. The splits in the MO and NE delegations are interesting.

In the spirit of trying to explain “errors” here, I’m wondering if any of our political science colleagues engaged in lobbying (seriously). For instance, did the Vandy people email Lamar Alexander? Did the UT/UH/Rice/Texas A&M people contact Cornyn’s office? And a lot of Federal research money finds it way to North Carolina, too (e.g., SAS, RTI, UNC & Duke, etc); Burr (R-NC) voted against the amendment, with an ideal point a long way to the right of the estimated cutpoint. Of course, it would also be interesting to consider cases where lobbying might have failed (McCaskill?).

Conversations with colleagues I was with yesterday (at the NSF!) had the more sensible take on this, probably to chalk it up to “position-taking”; with such a small amount of money at stake, the vote is largely symbolic (were that it were otherwise). That is, this is the kind of roll call that incumbents will add to their respective tallies in campaign statements to the effects of “I voted against waste and fraud n times…”


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