More on prior distributions for climate sensitivity

December 10, 2015
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In response to this post the other day on prior distributions for climate sensitivity, Nicholas Lewis wrote in: Your post refers to comments I made at ATTP’s blog about the use of Jeffreys’ prior in estimating climate sensitivity. I would like to explain why, in some but not all cases, the Jeffreys’ prior for estimating […] The post More on prior distributions for climate sensitivity appeared first on Statistical Modeling,…

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Who’s downloading the forecast package?

December 9, 2015
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Who’s downloading the forecast package?

The github page for the forecast package currently shows the following information Note the downloads figure: 264K/month. I know the package is popular, but that seems crazy. Also, the downloads figure on github only counts the downloads from the RStudio mirror, and ignores downloads from the other 125 mirrors around the world. Here are the […]

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Seasonal Unit Root Testing in EViews

December 9, 2015
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Seasonal Unit Root Testing in EViews

When we're dealing with seasonal data - e.g., quarterly data - we need to distinguish between "deterministic seasonality" and "stochastic seasonality". The first type of seasonality is what we try to remove when we "seasonally adjust" the series. It's ...

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By opposing tracking well-meaning educators are hurting disadvantaged kids

December 9, 2015
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By opposing  tracking well-meaning educators are hurting disadvantaged kids

An unfortunate fact about the US K-12 system is that the education gap between poor and rich is growing. One manifestation of this trend is that we rarely see US kids from disadvantaged backgrounds become tenure track faculty, especially in the STEM fields. In my experience, the ones that do make it, when asked how they overcame the

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Why I decided not to enter the $100,000 global warming time-series challenge

December 9, 2015
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Why I decided not to enter the $100,000 global warming time-series challenge

tl;dr: Negative expected return. Long version: I received the following email the other day from Tom Daula: Interesting applied project for your students, or as a warning for decisions under uncertainty / statistical significance. Real money on the line so the length of time and number of entries required to get a winner may be […] The post Why I decided not to enter the $100,000 global warming time-series challenge…

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Overlay categories on a histogram

December 9, 2015
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Overlay categories on a histogram

Recently Sanjay Matange blogged about how to color the bars of a histogram according to a gradient color ramp. Using the fact that bar charts and histograms look similar, he showed how to use PROC SGPLOT in SAS to plot a bar chart in which each bar is colored according […] The post Overlay categories on a histogram appeared first on The DO Loop.

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Fun media requests

December 8, 2015
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Lots of time I get asked who I think will win the election. This time we have something different: On Dec 8, 2015, at 2:59 AM, ** wrote: Hello Mr Gelman, I am writing you on behalf of ** Online Media **. We are a special service that finds the best experts to answer the […] The post Fun media requests appeared first on Statistical Modeling, Causal Inference, and Social…

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How Could Classification Trees Be So Fast on Categorical Variables?

December 8, 2015
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How Could Classification Trees Be So Fast on Categorical Variables?

I think that over the past months, I have been saying non-correct things about classification with categorical covariates. Because I never took time to look at it carefuly. Consider some simulated dataset, with a logistic regression, > n=1e3 > set.seed(1) > X1=runif(n) > q=quantile(X1,(0:26)/26) > q[1]=0 > X2=cut(X1,q,labels=LETTERS[1:26]) > p=exp(-.1+qnorm(2*(abs(.5-X1))))/(1+exp(-.1+qnorm(2*(abs(.5-X1))))) > Y=rbinom(n,size=1,p) > df=data.frame(X1=X1,X2=X2,p=p,Y=Y) Here, we use some continuous covariate, except that is considered as not-observed. Instead, we have a categorical covariate…

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Many rules of statistics are wrong

December 8, 2015
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Many rules of statistics are wrong

There are two kinds of people who violate the rules of statistical inference: people who don't know them and people who don't agree with them.  I'm the second kind.The rules I hold in particular contempt are:The interpretation of p-values: Suppose...

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Hierarchical modeling when you have only 2 groups: I still think it’s a good idea, you just need an informative prior on the group-level variation

December 8, 2015
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Dan Chamberlain writes: I am working on a Bayesian analysis of some data from a randomized controlled trial comparing two different drugs for treating seizures in children. I have been using your book as a resource and I have a question about hierarchical modeling. If you have the time, I would greatly appreciate any advice […] The post Hierarchical modeling when you have only 2 groups: I still think it’s…

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Probabilistic Integration

December 8, 2015
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Probabilistic Integration

Mark Girolami sends along a new paper by Francois-Xavier Briol, Chris Oates, Michael Osborne, Dino Sejdinovic, and himself. The idea is to consider numerical integration as a statistical problem, to say that the integral being estimated is an unknown parameter and then to perform inference about it. This is related to ideas of Xiao-Li Meng, […] The post Probabilistic Integration appeared first on Statistical Modeling, Causal Inference, and Social Science.

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Write unit tests!

December 7, 2015
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Write unit tests!

Since 2000, I’ve been working on R/qtl, an R package for mapping the genetic loci (called quantitative trait loci, QTL) that contribute to variation in quantitative traits in experimental crosses. The Bioinformatics paper about it is my most cited; also see my 2014 JORS paper, “Fourteen years of R/qtl: Just barely sustainable.” It’s a bit […]

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Two peas in a pod

December 7, 2015
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Two peas in a pod

Earlier today I've seen this post about Frank Wilcoxon's work on non-parametric statistics, on the Significance website. I've only very recently become involved in using some non-parametric methods (notably for our work on the EVPPI...

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Statbusters: standing may or may not stand a chance

December 7, 2015
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In our latest Statbusters column for the Daily Beast, we read the research behind the claim that "standing reduces odds of obesity". Especially at younger companies, it is trendy to work at standing desks because of findings like this. We find a variety of statistical issues calling for better studies. For example, the observational dataset used provides no clue as to whether sitting causes obesity or obesity leads to more…

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Use of Jeffreys prior in estimating climate sensitivity

December 7, 2015
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Use of Jeffreys prior in estimating climate sensitivity

William Morris writes: A discussion of the use of Bayesian estimation in calculating climate sensitivity (to doubled CO2) occurred recently in the comments at the And Then There’s Physics (ATTP) blog. One protagonist, ‘niclewis’, a well known climate sensitivity researcher, uses the Jeffreys prior in his estimations. His estimations are always at the low end […] The post Use of Jeffreys prior in estimating climate sensitivity appeared first on Statistical…

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On deck this week

December 7, 2015
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Mon: Use of Jeffreys prior in estimating climate sensitivity Tues: Hierarchical modeling when you have only 2 groups: I still think it’s a good idea, you just need an informative prior on the group-level variation Wed: I definitely wouldn’t frame it as “To determine if the time series has a change-point or not.” The time […] The post On deck this week appeared first on Statistical Modeling, Causal Inference, and…

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Why doesn’t PROC UNIVARIATE support certain common distributions?

December 7, 2015
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Why doesn’t PROC UNIVARIATE support certain common distributions?

A SAS customer asked: Why isn't the chi-square distribution supported in PROC UNIVARIATE? That is an excellent question. I remember asking a similar question when I first started learning SAS. In addition to the chi-square distribution, I wondered why the UNIVARIATE procedure does not support the F distribution. These are […] The post Why doesn't PROC UNIVARIATE support certain common distributions? appeared first on The DO Loop.

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NYC Stan meetup 12 December

December 7, 2015
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The next NYC Stan meetup is on Saturday: Feel free to bring things you’re working on or join in on projects some of the others are working on. A couple of the developers will be around to answer questions and help out. If you don’t have anything to work on, the Stan team could use […] The post NYC Stan meetup 12 December appeared first on Statistical Modeling, Causal Inference,…

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New Review of Forecasting at Bank of England

December 7, 2015
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Check it out here. It's thorough and informative.  It's interesting and unfortunate that even the Bank of England, the great "fan chart pioneer," produces density forecasts for only three of eleven variables forecasted (p. 15). In my view, the mos...

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Cannabis/IQ follow-up: Same old story

December 6, 2015
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Ole Rogeberg writes: The way researchers respond to criticism is a recurring theme on your blog, so you might find this amusing as a brief follow-up on the cannabis/IQ discussion you’ve covered before: The Dunedin longitudinal study has now been going for 40 years, and the lead researchers in charge of the study recently published an […] The post Cannabis/IQ follow-up: Same old story appeared first on Statistical Modeling, Causal Inference,…

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Venezuelan Parliamentary Election: What do the Polls Say?

December 6, 2015
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Venezuelan Parliamentary Election: What do the Polls Say?

There is not a huge population of opinion polls covering this parliamentary election in Venezuela, but all I’ve can be used to gauge the public opinion by the local polling houses. This posting begs an obvious question: how has the mood in Venezuela ...

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Venezuelan Parliamentary Election: What do the Polls Say?

December 6, 2015
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Venezuelan Parliamentary Election: What do the Polls Say?

There is not a huge population of opinion polls covering this parliamentary election in Venezuela, but all I’ve can be used to gauge the public opinion by the local polling houses. This posting begs an obvious question: how has the mood in Venezuela ...

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Venezuelan Parliamentary Election: What do the Polls Say?

December 6, 2015
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Venezuelan Parliamentary Election: What do the Polls Say?

There is not a huge population of opinion polls covering this parliamentary election in Venezuela, but all I’ve can be used to gauge the public opinion by the local polling houses. This posting begs an obvious question: how has the mood in Venezuela ...

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