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Year: 2013

By Posted on Posted in Methods No Comments

John Sides at the Monkey Cage discusses an article on public broadcasting and political knowledge. The cross-sectional survey data analyzed in the article cannot resolve the question of causal direction, as Sides notes:

Obviously, there are challenges of sorting out correlation and causation here. Do people who consume public broadcasting become more knowledgeable? Or are knowledgeable people just more likely to consume public broadcasting? Via statistical modeling, Soroka and colleagues go some distance in isolating the possible effects of public broadcasting—though they are clear that their modeling is no panacea.
Nevertheless, the results are interesting. In most countries, people who consume more public broadcasting know more about current events than people who consume less of it. But these same differences emerge to a lesser extent among those who consume more or less commercial broadcasting. This suggests that public broadcasting helps citizens learn. Here's a graph:
soroka

But the article should not be interpreted as providing evidence that "public broadcasting helps citizens learn."

Cross-sectional survey data cannot resolve the question of causal direction, but theory can: if we observe a correlation between, say, race and voting for a particular political party, we can rule out the possibility that voting for a particular political party is causing race.

Notice that in the United Kingdom, consumption of commercial broadcasting news correlates with a substantial decrease in political knowledge: therefore, if the figure is interpreted as evidence that broadcasting causes knowledge, then it is necessary to interpret the UK results as commercial broadcasting news in the UK causing people to have less political knowledge. I think that we can safely rule out that possibility.

The results presented in the figure are more likely to reflect self-selection: persons in the UK with more political knowledge choose to watch public broadcasting news, and persons in the UK with less political knowledge choose to watch commercial broadcasting news; that doesn't mean that public broadcasting has zero effect on political knowledge, but it does mean that the evidence presented in the figure does not provide enough information to assess the magnitude of the effect.

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By Posted on Posted in Law and courts No Comments

David Karol at Monkey Cage discusses the Supreme Court:

The broader point is that the whims of one unaccountable person, whatever their age, abilities or ideology should NOT matter so much in a democracy.

Karol proposes eighteen-year terms, which reduce the length of time that the "whims of one unaccountable person" matter but do not reduce the relative importance of that person's whims on any given case or in any given year. But court expansion would reduce the "cross-sectional" power of a justice and thus reduce the associated concern for the health of like-minded justices, severely curtailing the chance of a judicial Weekend at Bernie's.

Of course, it is not politically feasible to give any president multiple new nominations, but it is possible to expand the Court to eighteen members without packing and with minimal disruption to the status quo:

  1. Give each current justice two votes and each new justice one vote: when a current justice vacates a seat, the president and the Senate replace the current justice with two new justices; when a new justice vacates a seat, the president and the Senate replace the new justice with one new justice.
  2. Let's say that we want an eighteen-member Court immediately. Let each sitting justice nominate one new justice. The sitting justices would have a strong incentive to nominate a candidate with similar judicial and ideological views.

Eighteen-member or eighteen-vote Courts would have a greater potential for tie votes, but this is less a problem than a feature with positive consequences, since a majority of the full Court is now a 10-to-8 supermajority, which makes it slightly more difficult for the Court to overrule a lower court or alter its own precedent.

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By Posted on Posted in Teaching No Comments

This post at Active Learning in Political Science describes a discussion on inequality that followed the unequal distribution of chocolate to students reflecting unequal GDPs among countries:

The students then led a discussion about how the students felt, whether the wealthy students were obligated to give up some of their chocolate, and how they would convince the wealthy students to do so. Violence entered the conversation (jokingly) at one point. Eventually the discussion turned to the real-world implications, and the chocolate was widely shared.

Use of a prop like chocolate has advantageous qualities, such as raising the interest level of students and the uniqueness of the discussion, which likely fosters the potential for learning. But the simulation itself clouded or removed many of the features of inequality necessary for a quality discussion of global inequality and aid:

  1. A discussion of inequality among students in the same room diverts attention from impediments to sharing that real countries face: it is nearly costless to pass chocolate to the person next to you, but there is a substantial cost to packaging and shipping goods across the world.
  2. Presumably none of the students had the negative features of a regime like North Korea that would raise questions about whether direct aid might be more harmful than beneficial.
  3. The method of production of the chocolate in the simulation bears no relationsip to the method of production for GDP, chocolate, or any good in the real world: countries do not "receive" goods or wealth independent of mechanisms related to the country's natural resources, education or skill level of the population, political choices, history, etc.
  4. The parameters of the simulation ensured that the total amount of chocolate was static, so that the producion of more chocolate was not an option for the students.

The problem with simulations such as this is that the focus is placed on the simulated instead of the real.

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By Posted on Posted in Law and courts No Comments

High LSAT scores in a given major have been used to recruit students into philosophy and physics. But high LSAT scores do not necessarily reflect the ability of a major to prepare students for the LSAT or for the legal profession, because students self-select into majors: high school students with an interest in philosophy or physics might already possess the verbal and analytical skills that the LSAT tests, so that high LSAT scores for philosophy or physics majors might reflect only the pre-existing abilities of students who select those majors.

The graph below illustrates this possibility with a plot of 2007 LSAT scores grouped by major against 2003 SAT scores grouped by intended major. Some majors have been combined* and control variables were not included in the analysis**, so the graph should be interepreted with caution: but the general pattern is a relatively high correlation between SAT scores and LSAT scores (r=0.89, n=16, p<0.01).

LSAT2007SAT2003

Sources: 2007 LSAT data from Nieswiadomy (2009), and 2003 SAT scores from the College Board.

* Accounting, Business Management, Business Administration, Finance, and Marketing majors were grouped into the Business intended major; Interdisciplinary Studies and Liberal Arts majors were grouped into the General Studies intended major; Chemistry and Physics/Math majors were grouped into the Physical Sciences intended major; Criminal Justice, Government/Service, and Pre-Law majors were grouped into the Public Services intended major; and Anthropology/Geography, Economics, History, International Relations, Political Science, Psychology, and Sociology/Social Work majors were grouped into the Social Sciences intended major.

** For example, the analysis does not account for students who drop out or students who switch majors; the analysis considers data for only the set of students who took the SAT in 2003 and the separate but presumably overlapping set of students who took the LSAT in 2007; the analysis also does not account for selection bias with regard to students sitting for the LSAT: for instance, mathematics majors who take the LSAT might be less intelligent or more intelligent than the average mathematics major.

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