## Intuition for Prediction Under Bregman Loss

October 6, 2014
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Elements of the Bregman family of loss functions, denoted $$B(y, \hat{y})$$, take the form:$$B(y, \hat{y}) = \phi(y) - \phi(\hat{y}) - \phi'(\hat{y}) (y-\hat{y})$$ where $$\phi: \mathcal{Y} \rightarrow R$$ is any strictly convex function, and \(\mathca...

## Convert hexadecimal colors to RGB

October 6, 2014
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In response to my recent post about how to use the PALETTE function in SAS/IML to generate color ramps, a reader wrote the following: The PALETTE function returns an array of hexadecimal values such as CXF03B20. For those of us who think about colors as RGB values, is there an […]

## TBATS with regressors

October 6, 2014
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I’ve received a few emails about including regression variables (i.e., covariates) in TBATS models. As TBATS models are related to ETS models, tbats() is unlikely to ever include covariates as explained here. It won’t actually complain if you include an xreg argument, but it will ignore it. When I want to include covariates in a […]

## A bit more fragmented

October 6, 2014
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The election gave rise to an even more fragmented lower chamber in Brazil. The 2014 legislative election This year, the election gave rise to an even more fragmented House. The way political scientists measure how fragmented is political system ...

## A bit more fragmented

October 6, 2014
By

The election gave rise to an even more fragmented lower chamber in Brazil. The 2014 legislative election This year, the election gave rise to an even more fragmented House. The way political scientists measure how fragmented is political system ...

## A bit more fragmented

October 6, 2014
By

The election gave rise to an even more fragmented lower chamber in Brazil. The 2014 legislative election This year, the election gave rise to an even more fragmented House. The way political scientists measure how fragmented is political system ...

## Monte Carlo simulation and resampling methods for social science [book review]

October 5, 2014
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Monte Carlo simulation and resampling methods for social science is a short paperback written by Thomas Carsey and Jeffrey Harden on the use of Monte Carlo simulation to evaluate the adequacy of a model and the impact of assumptions behind this model. I picked it in the library the other day and browse through the […]

## A Statistics-centric curriculum

October 5, 2014
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Calculus is the wrong summit of the pyramid. “The mathematics curriculum that we have is based on a foundation of arithmetic and algebra. And everything we learn after that is building up towards one subject. And at top of that … Continue reading →

## Evil companies, stereotypes and coffee

October 5, 2014
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A couple of weeks ago, our favourite coffee place in Walton (where we live) just closed out of the blue. We were really surprised as we thought they were doing really well, as the shop was almost always buzzing with people. So we did a bit of inve...

## Bayes of thrones

October 5, 2014
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My friend and colleague Andreas sent me a link to a working paper published by a statistician at the University of Christchurch (New Zealand) and discussed here. The main idea of the paper was to use a Bayesian model to predict the number of futur...

## Anova is great—if you interpret it as a way of structuring a model, not if you focus on F tests

October 5, 2014
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Shravan Vasishth writes: I saw on your blog post that you listed aggregation as one of the desirable things to do. Do you agree with the following argument? I want to point out a problem with repeated measures ANOVA in talk: In a planned experiment, say a 2×2 design, when we do a repeated measures […]

## Bayes models from SAS PROC MCMC in R, post 2

October 5, 2014
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This is my second post in converting SAS's PROC MCMC examples in R. The task in his week is determining the transformation parameter in a Box-Cox transformation. SAS only determines Lambda, but I am not so sure about that. What I used to do was get an ...

## Diederik Stapel hired to teach “social philosophy” because students got tired of success stories… or something (rejected post)

October 5, 2014
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Oh My*. (“But I can succeed as a social philosopher”) The following is from Retraction Watch. UPDATE: OCT 10, 2014** “Curtain up on second act for Dutch fraudster Stapel: College teacher” Diederik Stapel, the Dutch social psychologist and admitted data fabricator — and owner of 54 retraction notices — is now teaching at a college in the town of […]

## On efficient algorithms for finding the goddamn endnotes

October 4, 2014
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IntroductionIn many recent books, the goddamn endnotes are numbered sequentially within each chapter, but chapter numbers seldom appear in the header on each page.  So a reader who wants to find a goddamn endnote typically has to search backward t...

## Carrie McLaren was way out in front of the anti-Gladwell bandwagon

October 4, 2014
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Here she was back in 2005, way before Gladwell-bashing became cool.

## World Wide Wage

October 4, 2014
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South Koreans earn, on average, $33,140 per year (PPP), making them almost as rich as Britons. However, Koreans also work 30% more hours than Britons, making their per-hour wage considerably less than a British wage. In fact, the Korean wage of$15 per hour (PPP) is comparable to that of a Czech or Slovakian. Here […]

## A patently pointless picture

October 3, 2014
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I am mystified by the intention behind this chart, published in NYT Magazine (Sept 14, 2014). It is not a data visualization since the circles were not placed to scale. The 650 and 660 should have been further to the...

## 65% of principals say that at least 30% of students . . . wha??

October 3, 2014
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Alan Sloane writes: The OECD put out a report drawing on their PISA and TALIS data: http://oecdeducationtoday.blogspot.ie/2014/07/poverty-and-perception-of-poverty-how.html I notice that it’s already attracted a NY Times op-ed by David Leonhart: http://www.nytimes.com/2014/07/23/upshot/principals-in-us-are-more-likely-to-consider-their-students-poor.html There are a number of things I find strange in its analysis and interpretation but, for starters, there’s the horizontal axis in the chart […]

## Ebola: Beds, Labs, and Warnings? Can they help? (Shiny App)

October 3, 2014
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A month ago when the WHO was projecting estimates of the effect of current outbreak of Ebola being as deadly as affecting 20,000 people, I ran some elementary modelling and found that these estimates are far too small given the current trend.  The...

## Which double letters appear most frequently in English text?

October 3, 2014
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Double, double toil and trouble; Fire burn, and caldron bubble.     Macbeth, Act IV, Scene I For the cyptanalyst or recreational puzzle solver, "double double" does not lead to toil or trouble. Just the opposite: The occurrence of a double-letter bigram in an enciphered word puzzle is quite fortunate. Certain double […]

## Consumer Preference Driven by Benefits and Affordances, Yet Management Sees Only Products and Features

October 3, 2014
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Return on Investment (ROI) is management's bottom line. Consequently, everything must be separated and assigned a row with associated costs and profits. Will we make more by adding another product to our line? Will we lose sales by limiting the feature...

October 2, 2014
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Our RSS feed is now directly accessible via andrewgelman.com/feed – no need to go through feedburner. You need to resubscribe to the feed.

## The Drake index for academics

October 2, 2014
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I think academic indices are pretty silly; maybe we should introduce so many academic indices that people can't even remember which one is which. There are pretty serious flaws with both citation indices and social media indices that I think render them pretty meaningless in a lot of ways. Regardless of these obvious flaws I