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    Michel and Liberman Aiden on "Quantitative Analysis of Culture Using Millions of Digitized Books"

    We hope that you can join us for the Applied Statistics Workshop tomorrow, March 2nd when we will be happy to have Jean-Baptiste Michel (Postdoctoral Fellow, Department of Psychology) and Erez Lieberman Aiden (Harvard Society of Fellows). You will find an abstract below. As always, we will serve a light lunch and the talk will begin around 12:15p.

    “...

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    Mind the Coding

    Here's something new to pick at, in addition to methods problems: coding isues. A recent Science (August 18, 2006, pages 979-982) article by Bruce Dohrenwend and colleagues reported on revised estimates of post traumatic stress disorders of Vietnam veterans. See here for an NYT article. The new study indicates that some 18.7% of Vietnam veterans developed diagnosable post-traumatic stress, compared with earlier estimates of 30.9%. The differences comes mainly from using revised measures of...

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    Misreading Racial Disparities - Beware Of Ratios of Percentages

    Felix Elwert

    It's fascinating how far you can get by taking a second look at the simplest statistics - in this case percentages and ratios. Case in point, James Scanlan's clever and unjustly ignored observation that African Americans will necessarily appear to be losing ground relative to whites even as their standing improves in absolute terms. (Actually, the argument holds for any inter-group comparisons, not just race.) Scanlan shows that this is an artifact of measuring progress by focusing exclusively on ratios of percentages from dissimilar distributions...

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    Missing Women and Sex-Selective Abortion

    You, Jong-Sung

    The problem of “missing women��? in many developing countries reflects not just the gender inequality but serious violation of human rights, as Amartya Sen reported in his book Development as Freedom (1999). It refers to the phenomenon of excess mortality and artificially lower survival rates of women. Particularly disturbing is the practice of sex-selective abortion, which has become quite widespread in China and South Korea.

    Statistical analysis, in particular examination of anomalies in a distribution of interest, can give...

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    Misunderestimating Sampling Error with CNN's Poll of Polls

    The good folks at CNN are hot on the trail of a swing to McCain in Ohio, a crucial battleground state. CNN's headline claims, "Ohio Poll of Polls: McCain Gains Some Ground in Tight Race". From the story , we learn that,

    "CNN's new Ohio poll of polls shows Barack Obama leading McCain by three points, 49 to 46 percent. Five percent of the state's voters were unsure about their presidential pick.
    The network's last Ohio poll of polls, released October 9, showed...

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    Misunderstandings among Experimentalists and Observationalists

    We had several discussions a while ago on this blog about balance test fallacies, and an early version of a paper on the subject that Kosuke Imai, Liz Stuart and I wrote. Kosuke, Liz, and I also had a number of interesting discussions with people in several other fields about this topic, and we've found much confusion about the benefits of the key portions of the major research designs. Observationalists seem to have experiment-envy, which is in at least some cases unwarrented, and experimentalists have their own related issues too. To sort these issues out (largely or at least at first...

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    More on Affirmative Action

    Felix Elwert

    It's well known that African American college students on average (repeat: on average) have lower SAT scores than white students (see Bowen and Bok's book The Shape of the River). Now here's something that annoys me: Every now and then, I run into somebody who takes this observation as evidence that affirmative action dilutes academic standards. Hello? Differences in mean SATs among accepted students have little or nothing to do with affirmative action!!

    Consider this: SAT scores are roughly normally distributed among both blacks and whites...

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    More on Cheating

    In my last post, I solicited comments on ways to cheat when using a design-before-analysis framework for analyzing observational studies. My claim was that if one does the hard work of distinguishing intermediate outcomes from covariates (followed usually by discarding the former) and of balancing the covariates (often done by discarding non-comparable observations) without access to the outcome variable, it should be hard(er) to cheat....

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    More on Standards and Statistical Measures of Partisan Gerrymandering

    For those interested in more detail about the Texas Redistricting case, and associated Amici brief, that Drew Thomas wrote about a few entries ago, you might be interested in The Future of Partisan Symmetry as a Judicial Test for Partisan Gerrymandering after LULAC v. Perry, by Bernie Grofman and me, forthcoming in the Election Law Journal. An abstract appears below. Comments welcome!

    While the Supreme Court in Bandemer v. Davis found partisan gerrymandering to be justiciable, no challenged...

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    More on statistics and the death penalty

    There was a good non-technical article by Adam Liptak in the New York Times this weekend reviewing the renewed debate about the supposed deterrent effect of capital punishment (The web version of the article linked to seven different academic articles; many thanks to the editorial staff). I've blogged about this before (here) and tend to agree with those who say that there just isn't enough information...

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    More Questions About Balance (And No Answers)

    Jim Greiner

    The recent posts on achieving good balance within matching have stimulated a certain amount of interest. To this debate I offer more questions and, alas, no answers, which are what I'd really like to know. (For what it's worth, I am not doing research in this area. All of my questions are genuine, not rhetorical.)

    As I understand it, the genetic algorithm that Diamond and Sekhon favor searches for matches that minimize p-values from hypothesis tests. The subject of the...

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    More SUTVA questions

    Since Jim's post has brought us back to the SUTVA problem, here is another situation to consider. Let's say that I am interested in the effect of starting order on the performance of athletes in some competition. For the sake of argument, let's say cycling. We might conjecture that starting in the first position in a pack of cyclists conveys some advantage, since the leader can stay out of trouble in the back of the pack. On the other hand, there might be an advantage to starting in a lower position so that the cyclist can take advantage of the draft behind the leaders.

    It is...

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    Mother Nature Estimates Using...?

    So it's finally getting cold in Boston after some days that resembled Spring more than anything. Outside the buildings, smokers in T-shirts and flip-flops? The first flowers blooming?? But it's not all lost: I was just reading that an early Spring or a short interval of warm temperatures doesn't really matter for plants and animals. Plants just grow new buds or skip a year. Animals adjust their sleep patterns. But maybe Mother Nature is also smart about predicting when it's the right time to wake up. Are plants and animals Bayesians and have learned to give more weight to a signal...

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    Mullainathan on How We Choose: Medicare Drug Plan Selection

    Please join us for the final applied statistics workshop of the semester when Sendhil Mullainathan, Professor of Economics Harvard University,
    will present 'How We Choose: Medicare Drug Plan Selection', work that is joint with Jeff Kling, Eldar Shafir, Lee Vermeulen, and Marian Wrobel.
    Sendhil provided the following abstract:

    Choices increasingly abound for various government supported services, ranging from charter schools to health plans. 24 million elderly Americans have enrolled in Medicare Part D prescription drug coverage during the past two years, and may choose...

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    Multilevel Hazard Models in Log-Time Metric?

    Felix Elwert

    Has anybody figured out how to estimate multilevel hazard models with time-varying covariates in log-time metric (i.e., an accelerated failure time model)?

    Together with two colleagues from the Medical School, I’m working on the effect of contextual variables on mortality. We're using a large longitudinal dataset of around ½ million married couples and nine years of follow up. Our key independent variable is time varying. In recent years, much work has been done on multilevel hazard models, for example, that done by Harvey Goldstein and...

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    Multiple comparisons and the "Axe" effect


    Like many of us, I'm always on the lookout for good examples to use in undergraduate methods courses. My high school chemistry teacher (a former nun) said that the best teaching examples involved sex, food, or money, and that seems like reasonable advice for statistics as well. In that vein, I noted a recent article on the "Axe effect" in Metro:

    'Axe effect' really works, a new study swears

    Researchers in the U.K. asked women to rate the attractiveness of men wearing Axe's British counterpart, Lynx, against those who were wearing an odorless placebo.

    ...

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    Multiple Instruments

    I recently found a paper by Angus Deaton that attempts to (1) discount the usefulness of instrumental variables for making causal inferences in development economics and (2) discount the usefulness of field experiments. He has definitely stirred the pot a little and is now part of an interesting debate, although the discussion seems to be more focused on Deaton's controversial claims about experiments.

    ... Read more about Multiple Instruments

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