Yair prepared this graph of average district vote (imputing open seats at 75%/25%; see here for further discussion of this issue) for each House election year since 1976: Decades of Democratic dominance persisted through 1992; since then the two parties have been about even. As has been widely reported, a mixture of geographic factors and […]

## “Do you have any recommendations for useful priors when datasets are small?”

A statistician who works in the pharmaceutical industry writes: I just read your paper (with Dan Simpson and Mike Betancourt) “The Prior Can Often Only Be Understood in the Context of the Likelihood” and I find it refreshing to read that “the practical utility of a prior distribution within a given analysis then depends critically […]

## Prior distributions for covariance matrices

Someone sent me a question regarding the inverse-Wishart prior distribution for covariance matrix, as it is the default in some software he was using. Inverse-Wishart does not make sense for prior distribution; it has problems because the shape and scale are tangled. See this paper, “Visualizing Distributions of Covariance Matrices,” by Tomoki Tokuda, Ben Goodrich, […]

## Should we be concerned about MRP estimates being used in later analyses? Maybe. I recommend checking using fake-data simulation.

Someone sent in a question (see below). I asked if I could post the question and my reply on blog, and the person responded: Absolutely, but please withhold my name because this is becoming a touchy issue within my department. The boldface was in the original. I get this a lot. There seems to be […]

## My footnote about global warming

At the beginning of my article, How to think scientifically about scientists’ proposals for fixing science, which we discussed yesterday, I wrote: Science is in crisis. Any doubt about this status has surely been been dispelled by the loud assurances to the contrary by various authority figures who are deeply invested in the current system […]

## Latour Sokal NYT

Alan Sokal writes: I don’t know whether you saw the NYT Magazine’s fawning profile of sociologist of science Bruno Latour about a month ago. I wrote to the author, and later to the editor, to critique the gross lack of balance (and even of the most minimal fact-checking). No reply. So I posted my critique […]

## A parable regarding changing standards on the presentation of statistical evidence

Now, the P-value Sneetches Had tables with stars. The Bayesian Sneetches Had none upon thars. Those stars weren’t so big. They were really so small. You might think such a thing wouldn’t matter at all. But, because they had stars, all the P-value Sneetches Would brag, “We’re the best kind of Sneetch on the Beaches. […]

## Niall Ferguson and the perils of playing to your audience

History professor Niall Ferguson had another case of the sillies. Back in 2012, in response to Stephen Marche’s suggestion that Ferguson was serving up political hackery because “he has to please corporations and high-net-worth individuals, the people who can pay 50 to 75K to hear him talk,” I wrote: But I don’t think it’s just […]

## “Statistical insights into public opinion and politics” (my talk for the Columbia Data Science Society this Wed 9pm)

7pm in Fayerweather 310: Why is it more rational to vote than to answer surveys (but it used to be the other way around)? How does this explain why we should stop overreacting to swings in the polls? How does modern polling work? What are the factors that predict election outcomes? What’s good and bad […]

## Bayes, statistics, and reproducibility: “Many serious problems with statistics in practice arise from Bayesian inference that is not Bayesian enough, or frequentist evaluation that is not frequentist enough, in both cases using replication distributions that do not make scientific sense or do not reflect the actual procedures being performed on the data.”

This is an abstract I wrote for a talk I didn’t end up giving. (The conference conflicted with something else I had to do that week.) But I thought it might interest some of you, so here it is: Bayes, statistics, and reproducibility The two central ideas in the foundations of statistics—Bayesian inference and frequentist […]

## My talk tomorrow (Tues) noon at the Princeton University Psychology Department

Integrating collection, analysis, and interpretation of data in social and behavioral research Andrew Gelman, Department of Statistics and Department of Political Science, Columbia University The replication crisis has made us increasingly aware of the flaws of conventional statistical reasoning based on hypothesis testing. The problem is not just a technical issue with p-values, not can […]

## In which I demonstrate my ignorance of world literature

Fred Buchanan, a student at Saint Anselm’s Abbey School, writes: I’m writing a paper on the influence of Jorge Luis Borges in academia, in particular his work “The Garden of Forking Paths”. I noticed that a large number of papers from a wide array of academic fields include references to this work. Your paper, “The […]

## The p-value is 4.76×10^−264

Jerrod Anderson points us to Table 1 of this paper: It seems that the null hypothesis that this particular group of men and this particular group of women are random samples from the same population, is false. Good to know. For a moment there I was worried. On the plus side, as Anderson notes, the […]

## “James Watson in his own words”

Here are some thoughts from the noted biologist and writer, collected by Lior Pachter. I’d seen a few of these Watson quotes before, but it’s kinda stunning to see them all in one place. Apparently he recommends never adopting an Irish kid. All right, then.

## Stephen Wolfram explains neural nets

It’s easy to laugh at Stephen Wolfram, and I don’t like some of his business practices, but he’s an excellent writer and is full of interesting ideas. This long introduction to neural network prediction algorithms is an example. I have no idea if Wolfram wrote this book chapter himself or if he hired one of […]

## “And when you did you weren’t much use, you didn’t even know what a peptide was”

Last year we discussed the story of an article, “Variation in the β-endorphin, oxytocin, and dopamine receptor genes is associated with different dimensions of human sociality,” published in PNAS that, notoriously, misidentified what a peptide was, among other problems. Recently I learned of a letter published in PNAS by Patrick Jern, Karin Verweij, Fiona Barlow, […]

## Multilevel models for multiple comparisons! Varying treatment effects!

Mark White writes: I have a question regarding using multilevel models for multiple comparisons, per your 2012 paper and many blog posts. I am in a situation where I do randomized experiments, and I have a lot of additional demographic information about people, as well. For the moment, let us just assume that all of […]

## $ vs. votes

Carlos Cruz writes: Here’s an economics joke. Two economists are walking along when they happen to end up in front of a Tesla showroom. One economist points to a shiny new car and says, “I want that!” The other economist replies, “You’re lying.” The premise of this joke is that if the one economist had […]

## “Economic predictions with big data” using partial pooling

Tom Daula points us to this post, “Economic Predictions with Big Data: The Illusion of Sparsity,” by Domenico Giannone, Michele Lenza, and Giorgio Primiceri, and writes: The paper wants to distinguish between variable selection (sparse models) and shrinkage/regularization (dense models) for forecasting with Big Data. “We then conduct Bayesian inference on these two crucial parameters—model […]

## These 3 problems destroy many clinical trials (in context of some papers on problems with non-inferiority trials, or problems with clinical trials in general)

Paul Alper points to this news article in Health News Review, which says: A news release or story that proclaims a new treatment is “just as effective” or “comparable to” or “as good as” an existing therapy might spring from a non-inferiority trial. Technically speaking, these studies are designed to test whether an intervention is […]