Wednesday April 29, 2009

Filed under: politics,statistics — jackman @ 5:37 pm

I estimate that Specter was the 3rd most liberal Republican; see the (thumbnail) graph below, based on all recorded votes of the (current) 111th U.S. Senate.


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data wars (can you trust Internet samples?)

Wednesday April 22, 2009

Filed under: politics,statistics — jackman @ 3:57 pm

Gary Langer, the Director of Polling at ABC News discusses the properties of “opt-in” Internet samples. His chief gripe: “you need a probability sample to compute sampling error” and so any opt-in Internet poll that reports a standard error is lying.

This is a really important issue, since internet polling is not going away: its too fast, too cheap, and can generate big samples in a hurry; there is a lot to be said for self-completion and presenting multimedia content to respondents; and hence Internet is very attractive relative to other modes. So look for a response from proponents of opt-in sampling in the near future.

Observation: all survey respondents “opt-in”. Would-be respondents (selected via random sampling or not) decide whether to respond or not, or can’t be reached at all. We then weight the data we get to try to deal with any resulting biases. The resulting standard errors should be computed taking the weighting into account (in almost all media polling I see, they are not, and the standard error is computed a la Stats 101 with the number of completed interviews in the denominator), but in any event, even the correct standard errors are conditional on the way the weights were computed. The Stats 101 “textbook purity” of “simple random sampling” has long been left behind…particularly given some of the horror stories you hear about RDD response rates.

So I tend to think the “you can’t trust opt-in Internet polls” line is something of a beat-up. Sure, there is work to be done in understanding the properties of data generated this way, and how to compute a standard error with these data. I don’t see this as an impossible hill to climb. It is critical that this work get done, because if/when we can get comfortable with the bias issues (and we know what the issues are), then I think its game over.

If/when the bias issue more or less neutralized, Internet will most likely kill RDD in terms of sampling variability due to the huge effective sample sizes; exactly how much will turn on how much of a hit Internet takes in sampling variability when making bias adjustments, but that is going to have be a huge hit in order for RDD to wind up dominating Internet (given relative costs, and the fact that RDD is taking a variance hit too in making bias adjustments).

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AEC and Australian electoral standards

Saturday April 4, 2009

Filed under: Australian Politics — jackman @ 4:44 am

Mumble posted re the AEC and putting Australian electoral practices and standards into comparative perspective.

My $0.02. Australia looks good internationally with respect to election administration largely because of our long-standing embrace of compulsory voting, and a reasonably solid bipartisan consensus supporting that (the Howard government’s funny buggers with respect to enrollment requirements notwithstanding). Once you have CV on the books, and both sides of politics take it fairly seriously, then you have to administer the rolls, run elections, fine non-compliers etc, and then a body charged with election administration has to be created.

In short, if the state wants to make something compulsory, then it has to make compliance easy, and that is essentially one of the chief things the AEC does, and does pretty well (with the noted exception of enrollment).

Oh, and it would be nice if I could continue to vote even when living outside of Australia for an extended period (say what you want about the Americans, but they don’t disenfrachise their expatriate population).

The other thing is the nationalization of election administration in Australia, something that the Americans have never figured out in their particular version of federalism. It is entirely possible that Australia’s version of federalism could have left it to the state parliaments to run Commonwealth elections (a la America), and who knows how that might have played out (with or without CV). That never happened in Australia, leaving the way open for CV to be imposed nationally via Commonwealth legislation, and for the creation and evolution of a professional body like the AEO (later, the AEC).

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United prices slashed

Wednesday April 1, 2009

Filed under: flight nerdery — jackman @ 11:41 am

I don’t think I’ve ever seen prices this low…

Picture 1-27

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