Wednesday, 4 August 2004

Time keeps slipping

For some odd reason, the ntp server on my laptop refuses to keep sync with any servers on the Internet; instead, it’s decided to just go off and run several minutes slow, for some odd reason I can’t quite understand. Maybe it’s a 2.6.8-rc kernel bug or something. I noticed it yesterday too—my laptop lost nearly a half-hour over a day, somehow.

Once more into the breach

Stephen Bainbridge (via Glenn Reynolds) isn’t impressed with the use of NOMINATE scores to cast John Kerry as more of a centrist; nor is he particularly thrilled with methods like NOMINATE to begin with:

Personally, I find the interest group scores much more accessible and transparent. For one thing, NOMINATE counts all nonunanimous roll calls, which can include a lot of procedural and uncontroversial (even nonpartisan) bills. The interest group rankings focus on bills that really tell us something about the political philosophy of the candidate in question. For another, the interest group ratings are widely used both by the media and, perhaps more important, by politicians themselves.

I’d respond that NOMINATE (and related methods) are preferable to interest group scores precisely because they count all nonunanimous roll calls; this avoids the selection effect where interest groups choose, say, twenty “key” votes as a litmus test for an entire session. And, presumably, those who vote on party lines on “nonpartisan” and “uncontroversial” bills are even more partisan than those who join with their natural opposition. Another worthy point in favor of NOMINATE: the “procedural” versus “substantive” distinction is largely subjective; cloture votes in the Senate, for example, are technically procedural motions to end debate (and potentially stop a filibuster), while procedural votes on rules in the House often have serious substantive consequences (by ruling certain amendments out-of-order, framing and controlling debate, and sometimes even amending the legislation in question).

Now, Clinton, Jackman, and Rivers are quite correct to point out that the statistical properties of NOMINATE are, at best, nebulous, although Lewis and Poole recently made a worthy effort to gain additional leverage on the bias and uncertainty of NOMINATE in Political Analysis. And, while some of the differences in the results of the techniques are the result of differences between the distributional assumptions of NOMINATE and the CJR scaling method* (which explains the differing positions of Kerry in years in which he missed a lot of roll calls), there are some good reasons to prefer the CJR technique—most notably, it’s significantly more tractable; you can estimate the model almost trivially using MCMCpack.

Anyway, for those with a morbid curiosity about these techniques, the latest American Political Science Review has an article by Clinton, Jackman, and Rivers called “The Statistical Analysis of Roll-Call Data,” which I recommend highly (and which you may or may not be able to access via this link).

I’ve posted previously on NOMINATE and related methods (again, in relation to John Kerry’s voting record) here and here. This is my entry in today’s Beltway Traffic Jam.

* Technically speaking, it’s a Normal-theory two-parameter item-response theory model in two dimensions. If that doesn’t give you a headache, consider reading Ordinal Data Modeling by Johnson and Albert, who exposit the one-dimensional case rather nicely in a later chapter of their text.

Another gift from Memphis to the nation

Michael Totten has the scoop on the latest idiocy from the Memphis city council, this time perpetrated by city council chairman Joe Brown, who barred a group of visiting Iraqi officials from city hall, apparently out of concern that they were terrorists. Nor could the city or county mayor be bothered to meet with the group. On the bright side (?), at least they did get to meet mayoral aspirant and city councilwoman Carol Chumney, albeit not at city hall. Needless to say, Memphis-area residents are uniformly shocked, but not all that surprised, by this boorish behavior from their elected leaders.

One suspects that, overall, the Iraqis are better off not having had a chance to meet these rather dubious examples of American officialdom, lest they set a bad example.

Update: Mike Hollihan has more on the fallout from this mess; Chumney is making some political hay with the issue, but I honestly don’t see how she beats Herenton in a head-to-head contest, despite the latter apparently being under investigation by the FBI.

Textbook review

One of the little ways us wanna-be professors make a little side money (a couple hundred bucks a pop) is by reviewing textbooks for publishers. At the moment, I’m reviewing an American government textbook for its n+1th edition, which is nothing unusual, except what they sent me to review is the nth edition—which I already had a copy of at home anyway, since I was planning to adopt it for American government in the fall until O’Connor and Sabato was foisted upon me. So I guess I’m technically “pre-reviewing” it, or “post-reviewing” the nth edition, or something. And, in four chapters, I’ve only managed to come up with about a page of comments (and mostly silly stuff like “Unorthodox Lawmaking rocks, add it to the recommended readings on Congress,” rather than stuff like “only an idiot would write this paragraph”). I guess that means it’s a good book or something, but for $X I think they want more than a page of comments.