Bob writes, to someone who is doing work on the Stan language: The basic execution structure of Stan is in the JSS paper (by Bob Carpenter, Andrew Matt Hoffman, Daniel Lee, Ben Goodrich, Michael Betancourt, Marcus Brubaker, Jiqiang Guo, Peter Li, and Allen Riddell) and in the reference manual. The details of autodiff are in […]
Author: Andrew
Another Regression Discontinuity Disaster and what can we learn from it
As the above image from Diana Senechal illustrates, a lot can happen near a discontinuity boundary. Here’s a more disturbing picture, which comes from a recent research article, “The Bright Side of Unionization: The Case of Stock Price Crash Risk,” by Jeong-Bon Kim, Eliza Xia Zhang, and Kai Zhong: which I learned about from the […]
We should be open-minded, but not selectively open-minded.
I wrote this post awhile ago but it just appeared . . . I liked this line so much I’m posting it on its own: We should be open-minded, but not selectively open-minded. This is related to the research incumbency effect and all sorts of other things we’ve talked about over the years. There’s a […]
And, if we really want to get real, let’s be open to the possibility that the effect is positive for some people in some scenarios, and negative for other people in other scenarios, and that in the existing state of our knowledge, we can’t say much about where the effect is positive and where it is negative.
Javier Benitez points us to this op-ed, “Massaging data to fit a theory is not the worst research sin,” where philosopher Martin Cohen writes: The recent fall from grace of the Cornell University food marketing researcher Brian Wansink is very revealing of the state of play in modern research. Wansink had for years embodied the […]
How to think about reported life hacks?
Interesting juxtaposition as two interesting pieces of spam happened to appear in my inbox on the same day: 1. Subject line “Why the power stance will be your go-to move in 2019”: The power stance has been highlighted as one way to show your dominance at work and move through the ranks. While moving up […]
Freud expert also a Korea expert
I received the following email: Dear Dr Andrew Gelman, I am writing to you on behalf of **. I hereby took this opportunity to humbly request you to consider being a guest speaker on our morning radio show, on 6th August, between 8.30-9.00 am (BST) to discuss North Korea working on new missiles We would […]
How much is your vote worth?
Tyler Cowen writes: If it were legal, and you tried to sell your vote and your vote alone, you might not get much more than 0.3 cents. It depends where you live. If you’re not voting in any close elections, then the value of your vote is indeed close to zero. For example, I am […]
How to simulate an instrumental variables problem?
Edward Hearn writes: In an effort to buttress my own understanding of multi-level methods, especially pertaining to those involving instrumental variables, I have been working the examples and the exercises in Jennifer Hill’s and your book. I can find general answers at the Github repo for ARM examples, but for Chapter 10, Exercise 3 (simulating […]
“The writer who confesses that he is ‘not good at attention to detail’ is like a pianist who admits to being tone deaf”
Edward Winter wrote: It is extraordinary how the unschooled manage to reduce complex issues to facile certainties. The writer who confesses that he is ‘not good at attention to detail’ (see page 17 of the November 1990 CHESS for that stark, though redundant, admission by the Weekend Wordspinner) is like a pianist who admits to […]
Harvard dude calls us “online trolls”
Story here. Background here (“How post-hoc power calculation is like a shit sandwich”) and here (“Post-Hoc Power PubPeer Dumpster Fire”). OK, to be fair, “shit sandwich” could be considered kind of a trollish thing for me to have said. But the potty language in this context was not gratuitous; it furthered the larger point I […]
Random patterns in data yield random conclusions.
Bert Gunter points to this New York Times article, “How Exercise May Make Us Healthier: People who exercise have different proteins moving through their bloodstreams than those who are generally sedentary,” writing that it is “hyping a Journal of Applied Physiology paper that is now my personal record holder for most extensive conclusions from practically […]
I agree it’s a problem but it doesn’t surprise me. It’s pretty random what these tabloids publish, as they get so many submissions.
Jeff Lax writes: I’m probably not the only one telling you about this Science story, but just in case. The link points to a new research article reporting a failed replication of a study from 2008. The journal that published that now-questionable result refuses to consider publishing the replication attempt. My reply: I agree it’s […]
Causal inference: I recommend the classical approach in which an observational study is understood in reference to a hypothetical controlled experiment
Amy Cohen asked me what I thought of this article, “Control of Confounding and Reporting of Results in Causal Inference Studies: Guidance for Authors from Editors of Respiratory, Sleep, and Critical Care Journals,” by David Lederer et al. I replied that I liked some of their recommendations (downplaying p-values, graphing raw data, presenting results clearly) […]
The publication asymmetry: What happens if the New England Journal of Medicine publishes something that you think is wrong?
After reading my news article on the replication crisis, retired cardiac surgeon Gerald Weinstein wrote: I have long been disappointed by the quality of research articles written by people and published by editors who should know better. Previously, I had published two articles on experimental design written with your colleague Bruce Levin [of the Columbia […]
We’re done with our Applied Regression final exam (and solution to question 15)
We’re done with our exam. And the solution to question 15: 15. Consider the following procedure. • Set n = 100 and draw n continuous values x_i uniformly distributed between 0 and 10. Then simulate data from the model y_i = a + bx_i + error_i, for i = 1,…,n, with a = 2, b […]
Algorithmic bias and social bias
The “algorithmic bias” that concerns me is not so much a bias in an algorithm, so much as a social bias resulting from the demand for, and expectation of, certainty.
Pharmacometrics meeting in Paris on the afternoon of 11 July 2019
Julie Bertrand writes: The pharmacometrics group led by France Mentre (IAME, INSERM, Univ Paris) is very pleased to host a free ISoP Statistics and Pharmacometrics (SxP) SIG local event at Faculté Bichat, 16 rue Henri Huchard, 75018 Paris, on Thursday afternoon the 11th of July 2019. It will features talks from Professor Andrew Gelman, Univ […]
Question 15 of our Applied Regression final exam (and solution to question 14)
Here’s question 15 of our exam: 15. Consider the following procedure. • Set n = 100 and draw n continuous values x_i uniformly distributed between 0 and 10. Then simulate data from the model y_i = a + bx_i + error_i, for i = 1,…,n, with a = 2, b = 3, and independent errors […]
Question 14 of our Applied Regression final exam (and solution to question 13)
Here’s question 14 of our exam: 14. You are predicting whether a student passes a class given pre-test score. The fitted model is, Pr(Pass) = logit^−1(a_j + 0.1x), for a student in classroom j whose pre-test score is x. The pre-test scores range from 0 to 50. The a_j’s are estimated to have a normal […]
Naomi Wolf and David Brooks
Palko makes a good point: Parul Sehgal has a devastating review of the latest from Naomi Wolf, but while Sehgal is being justly praised for her sharp and relentless treatment of her subject, she stops short before she gets to the most disturbing and important implication of the story. There’s an excellent case made here […]