agelman | December 1, 2009Steven Levitt writes:
My view is that the emails [extracted by a hacker from the climatic research unit at the University of East Anglia] aren't that damaging. Is it surprising that scientists would try to keep work that disagrees with their findings out of journals? When I told my father that I was sending my work saying car seats are not that effective to medical journals, he laughed and said they would never publish it because of the result, no matter how well done the analysis was. (As is so often the case, he was right, and I eventually published it in an economics journal.)
Within the…
agelman | December 1, 2009Commenter RogerH pointed me to this article by Welton, Ades, Carlin, Altman, and Sterne on models for potentially biased evidence in meta-analysis using empirically based priors. The "Carlin" in the author list is my longtime collaborator John, so I really shouldn't have had to hear about this through a blog comment. Anyway, they write:
We present models for the combined analysis of evidence from randomized controlled trials categorized as being at either low or high risk of bias due to a flaw in their conduct. We formulate a bias model that incorporates between-study and between-meta-…
agelman | November 28, 2009Mark Rank and Thomas Hirschl recently published an estimate that 50% of American kids are on food stamps at some point during their first twenty years of life. Their estimate is based on an analysis of data from the Panel Study of Income Dynamics, from 1968 through 1997.
This news article by Lindsey Tanner provides a good overview.
The survey followed up families annually, thus there are kids in the study who were included at age 1, 2, . . ., 20. From this you can easily just count the proportion who were never on food stamps, the proportion who were on food stamps for one year during the…
agelman | November 27, 2009. . . where shooting someone in the head gets you four months in jail and a $1200 fine. Not a biggie, though--apparently it was only a "warning shot."
More generally, I don't know that prison is the solution to this sort of problem. If you put a violent criminal behind bars, he very well might be even more full of hatred and violence when he comes out. And, looking at it from the other way, it's hard to imagine that the threat of a prison sentence is enough to deter someone from this sort of behavior. I mean, what kind of person shoots an unarmed man in the head on the street in front of…
agelman | November 27, 2009
If this stuff is for real, it's really impressive. (Link from Aleks's twitter.)
agelman | November 26, 2009Julien Emile-Geay writes about a postdoc opportunity for a postdoc in climate
dynamics, applied statistics, or applied mathematics:
"Beyond the Hockey Stick: new approaches to paleoclimate reconstruction"
In 1998, a seminal study by Mann, Bradley and Hughes took advantage of climate signals embedded in an array of high-resolution paleoclimate proxy data to conclude that "Northern Hemisphere mean annual temperatures for three of the past eight years are warmer than any other year since (at least) AD 1400." The so-called "hockey stick" reconstruction showed relatively stable temperatures for…
agelman | November 25, 2009This is all standard physics. Consider the two-slit experiment--a light beam, two slits, and a screen--with y being the place on the screen that lights up. For simplicity, think of the screen as one-dimensional. So y is a continuous random variable.
Consider four experiments:
1. Slit 1 is open, slit 2 is closed. Shine light through the slit and observe where the screen lights up. Or shoot photons through one at a time, it doesn't matter. Either way you get a distribution, which we can call p1(y).
2. Slit 1 is closed, slit 2 is open. Same thing. Now we get p2(y).
3. Both slits are…
agelman | November 23, 2009I added a few entries recently. Currently, we have the following (in no particular order):
Mister P
The Secret Weapon
The Superplot
The Folk Theorem
The Pinch-Hitter Syndrome
Weakly Informative Priors
P-values and U-values
Conservatism
WWJD
Theoretical and Applied Statisticians
The Fallacy of the One-Sided Bet
Alabama First
The USA Today Fallacy
Second-Order Availability Bias
The "All Else Equal" Fallacy
The Self-Cleaning Oven
The Taxonomy of Confusion
The Blessing of Dimensionality
Scaffolding
Ockhamite Tendencies
Bayesian
Multiple Comparisons
agelman | November 22, 2009Seth reports on a report, funded by the sugar industry, that found bad effects of a diet soda additive called Splenda.
The background of the study is a delightful tangle. Seth reports:
One of the authors of the Duke study is a professor of psychiatry, Susan Schiffman. An earlier study of hers had pro-Splenda results. . . . Drs. Abou-Donia and Schiffman admitted that some of the results recorded in their report submitted to the court were not actually observed or were based on experiments that had not been conducted. . . .
Results in the report that were based on experiments that had not been…
agelman | November 22, 2009A colleague sent me an article by Harry Selker and Alastair Wood about the rules for comparative effectiveness research ("evidence-based medicine") in the House and Senate versions of the health-care bill. The key point:
The [Senate] Finance Committee bill also includes language requested by industry lobbyists (pages 1138-1139) that threatens to withdraw federal funding for 5 years from any investigator who publishes a report on research funded by the proposed institute that is not "within the bounds of and entirely consistent with the evidence." Determinations regarding such consistency…
agelman | November 22, 2009Christopher Nelson writes:
Check out the GDP chart under "The New Triad" here:
It's supposed to compare GDP in China, India, and the US for three time periods but for my money, it's composed wrong. The bars should be for the years, not the countries. That way we could see total GDP in each year and how it was composed of the respective GDPs. It would even be fairly easy to scan across and see how the country's GDP grew or shrank. What's there is just confusing.
I agree. Better to put time on the x-axis if possible. Then you don't need a bar plot at all, you can use a line plot, which I…
agelman | November 21, 2009Jimmy points me to this article, "Why most discovered true associations are inflated," by J. P. Ioannidis. As Jimmy pointed out, this is exactly what we call type M (for magnitude) errors. I completely agree with Ioannidis's point, which he seems to be making more systematically than David Weakliem and I did in our recent article on the topic.
My only suggestion beyond what Ioannidis wrote has to do with potential solutions to the problem. His ideas include: "being cautious about newly discovered effect sizes, considering some rational down-adjustment, using analytical methods that…
agelman | November 18, 2009Mark Thoma links to a report by Michael Shear on a leaked memo from the U.S. Chamber of Commerce:
The U.S. Chamber of Commerce and an assortment of national business groups opposed to President Obama's health-care reform effort are collecting money to finance an economic study that could be used to portray the legislation as a job killer and threat to the nation's economy, according to an e-mail solicitation from a top Chamber official.
The e-mail ... proposes spending $50,000 to hire a "respected economist" to study the impact of health-care legislation ... would have on jobs and the…
agelman | November 16, 2009The other day I commented on an article by Peter Bancel and Roger Nelson that reported evidence that "the coherent attention or emotional response of large populations" can affect the output of quantum-mechanical random number generators.
I was pretty dismissive of the article; in fact elsewhere I gave my post the title, "Some ESP-bashing red meat for you ScienceBlogs readers out there."
Dr. Bancel was pointed to my blog and felt I wasn't giving the full story. I'll give his comments and then at the end add some thoughts of my own. Bancel wrote:
I find it disappointing that a Columbia…
agelman | November 15, 2009I've been ranting lately about how I don't like the term "risk aversion," and I was thinking it might help to bring up this post from last year:
This discussion from Keynes (from Robert Skidelsky, linked from Steve Hsu) reminds me of a frustrating conversation I've sometimes had with economists regarding the concept of "risk aversion."
Risk aversion means many things, but in particular it is associated with attiitudes such as preferring a certain $30 to a 50/50 chance of having either $20 or $40. The standard model for this set of attitudes is to assume a nonlinear function for money. It is…
agelman | November 12, 2009A reporter contacted me to ask my impression of this article by Peter Bancel and Roger Nelson, which reports evidence that "the coherent attention or emotional response of large populations" can affect the output of quantum-mechanical random number generators.
I spent a few minutes looking at the article, and, well, it's about what you might expect. Very professionally done, close to zero connection between their data and whatever they actually think they're studying.
(Just for example, they mention that their random number generators are electromagnetically shielded--which seems kinda funny…
agelman | November 11, 2009Steve Levitt links to this article by Will Dobbie and Roland Fryer on an educational innovation to improve the education of ethnic minority children. Dobbie and Fryer write:
Harlem Children's Zone (HCZ) is arguably the most ambitious social experiment to alleviate poverty of our time. We [Dobbie and Fryer] provide the first empirical test of the causal impact of HCZ on educational outcomes, with an eye toward informing the long-standing debate whether schools alone can eliminate the achievement gap or whether the issues that poor children bring to school are too much for educators to…
agelman | November 11, 2009Jonathan Raban writes:
For an English-born reader, America is written in a language deceptively similar to one's own and full of pitfalls and 'false friends'. The word nature, for instance, means something different here - so do community, class, friend, tradition, home (think of the implications beneath the surface of the peculiarly American phrase 'He makes his home in ...').
I can't tell if Raban is being serious or if he is making some sort of joke. The paradox of the statement above is that very few readers will be qualified to assess it.
In any case, if someone can explain to me how…
agelman | November 10, 2009From blog commenter Lemmus comes this list of the 100 most visited Wikipedia pages in 2009.
The thing that I find hard to believe is that the number of hits on most of these articles is so low. For example, if I google "World War II," the Wikipedia entry comes up first. But according to the list linked to here, there were only 30,000 visits to the World War II Wikipedia page in all of 2009. I have similar problems with the other numbers. Could they really be so small as all that? Or am I thinking about this all wrong?
agelman | November 10, 2009One of the discussants in Brain and Behavioral Sciences of Seth Roberts's article on self-experimentation was by Martin Voracek and Maryanne Fisher. They had a bunch of negative things to say about self-experimentation, but as a statistician, I was struck by their concern about "the overuse of the loess procedure." I think lowess (or loess) is just wonderful, and I don't know that I've ever seen it overused.
Curious, I looked up "Martin Voracek" on the web and found an article about body measurements from the British Medical Journal. The title of the article promised "trend analysis" and I…