Hierarchical array priors for ANOVA decompositions

April 3, 2013
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Alexander Volfovsky and Peter Hoff write: ANOVA decompositions are a standard method for describing and estimating heterogeneity among the means of a response variable across levels of multiple categorical factors. In such a decomposition, the complete set of main effects and interaction terms can be viewed as a collection of vectors, matrices and arrays that [...]

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Bad charts can happen to good people

April 3, 2013
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Bad charts can happen to good people

I shouldn't be surprised by this. No sooner did I sing the praise of Significance magazine (link) than a reader sent me to some charts that are not deserving of their standard. Here is one such chart (link): Quite a...

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R 3.0.0 is released!

April 3, 2013
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R 3.0.0 is released!

The new R 3.0.0 is out! You know the drill! Get the source code from here.

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The difference of density estimates: When does it make sense?

April 3, 2013
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The difference of density estimates: When does it make sense?

I was recently asked how to compute the difference between two density estimates in SAS. The person who asked the question sent me a link to a paper from The Review of Economics and Statistics that contains several examples of this technique (for example, see Figure 3 on p. 16 [...]

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CFP: the 11th Australasian Data Mining Conference (AusDM 2013), submission extended to 31 July

April 3, 2013
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CFP: the 11th Australasian Data Mining Conference (AusDM 2013), submission extended to 31 July

********************************************************************* The 11th Australasian Data Mining Conference (AusDM 2013) Canberra, Australia, 13-15 November 2013, http://ausdm13.togaware.com Join us on LinkedIn: http://www.linkedin.com/groups/AusDM-4907891 ********************************************************************* Data mining, the art and science of intelligent analysis of (usually large) data sets for meaningful (and previously unknown) … Continue reading →

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Beware of grep with a list

April 3, 2013
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Beware of grep with a list

Another R tip: beware of as.character applied to a list. Really, beware of grep with a list: You might have thought that the result would be just 1, but grep expects a vector of character strings. If the input is not that, it uses as.character(). Since the result of that starts with "c(", grep finds […]

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apply vs for

April 3, 2013
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apply vs for

It’s widely understood that, in R programming, one should avoid for loops and always try to use apply-type functions. But this isn’t entirely true. It may have been true for Splus, back in the day: As I recall, that had to do with the entire environment from each iteration being retained in memory. Here’s a […]

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x[[c(5,3)]]

April 3, 2013
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x[[c(5,3)]]

An R tip: Did you know that x[[c(5,3)]] is the same as x[[5]][[3]]? I should make more thorough use of this. In the help file for [[: [[ can be applied recursively to lists, so that if the single index i is a vector of length p, alist[[i]] is equivalent to alist[[i1]]...[[ip]] providing all but […]

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Thoughts on statistical consulting

April 3, 2013
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Thoughts on statistical consulting

The Statistics Department at UW-Madison has a course on statistical consulting, offered each semester. I’m often asked to give a lecture, which I do in an informal way: summarizing my experiences and answering questions. I thought it might be useful write my thoughts on statistical consulting here: why, how, and difficulties. This will be a […]

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a brief on naked statistics

April 2, 2013
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a brief on naked statistics

Over the last Sunday breakfast I went through Naked Statistics: Stripping the Dread from the Data. The first two pages managed to put me in a prejudiced mood for the rest of the book. To wit: the author starts with some math bashing (like, no one ever bothers to tell us about the uses of [...]

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Petty in pink

April 2, 2013
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Petty in pink

I have to admit that in some sense I am being petty here. But I also think that this story is actually quite interesting, so I'm posting about it.As I've mentioned elsewhere in the blog (here and here), together with some colleagues I'm working on an e...

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100 savvy sites on statistics

April 2, 2013
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Online Math Degrees has a page of “100 savvy sites on statistics and quantitative analysis”.  It has some that you recognize, some that you’ve hardly ever heard of. The sites are divided into groups.  I think the R section should have included R-bloggers, but what do I know? I think it’s well worth strolling through. […]The post 100 savvy sites on statistics appeared first on Burns Statistics.

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A common theme in mathematics

April 2, 2013
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A common theme in mathematics

This is from a post Connected objects and a reconstruction theorem: A common theme in mathematics is to replace the study of an object with the study of some category that can be built from that object. For example, we can replace the study of a group  with the study of its category of linear representations, […]

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Estimating continuous piecewise linear regression

April 2, 2013
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Estimating continuous piecewise linear regression

When talking about smoothing splines a simple point to start with is a continuous piecewise linear regression with fixed knots. I did not find any simple example showing how to estimate the it in GNU R so I have created a little snippet that does the j...

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Introducing the healthvis R package – one line D3 graphics with R

April 2, 2013
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We have been a little slow on the posting for the last couple of months here at Simply Stats. That’s bad news for the blog, but good news for our research programs! Today I’m announcing the new healthvis R package … Continue reading →

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So much artistic talent

April 2, 2013
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So much artistic talent

I saw this excellent art show the other day, and it reminded me how much artistic talent is out there. I really have no idea whassup with those all-black canvases and the other stuff you see at modern art museums, given that there’s so much interesting new stuff being created every year. I see a [...]

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Top 10 tips to get started with R

April 2, 2013
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Top 10 tips to get started with R

Be motivated. R has a steep learning curve. Find a problem you can't solve otherwise. E.g. plotting multivariate data, a statistical analysis for which an R function exists already. Download and install R. Get to know the R console. Learn how to inst...

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Le Monde puzzle [#814]

April 1, 2013
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Le Monde puzzle [#814]

The #814 Le Monde math puzzle was to find 100 digits (between 1 and 10) such that their sum is equal to their product. Given the ten possible values of those digits, this is equivalent to finding integers a1,…,a10 such that a1+…+a10=100 and a1+2a2+…+10a10=2a2x….x10a10, which reduces the number of unknowns from 100 to 10 (or [...]

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Flawed Science and Stapel: Priming for a Backlash?

April 1, 2013
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Flawed Science and Stapel: Priming for a Backlash?

Deiderik Stapel is back in the news, given the availability of the English translation of the Tilberg (Levelt and Noort Committees) Report as well as his book, Ontsporing (Dutch for “Off the Rails”), where he tries to explain his fraud. An earlier post on him is here. While the disgraced social psychologist was shown to […]

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R: Installing, Loading, and Detaching Packages

April 1, 2013
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To install a package in R, the function to be used is install.packages. Let say we want to install the ggplot2 package, well simply code this withTo install more than one package, we do this byNote that in executing the above codes, a dialogue box...

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Wolfram on Mandelbrot

April 1, 2013
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Wolfram on Mandelbrot

The most perfect pairing of author and subject since Nicholson Baker and John Updike. Here’s Wolfram on the great researcher of fractals: In his way, Mandelbrot paid me some great compliments. When I was in my 20s, and he in his 60s, he would ask about my scientific work: “How can so many people take [...]

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R Tackles Big Garbage

April 1, 2013
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R Tackles Big Garbage

April 1, 2013 – Although the capabilities of the R system for data analytics have been expanding with impressive speed, it has heretofore been missing important fundamental methods. A new function works with the popular plyr package to provide these missing … Continue reading →

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A pictorial history of US large cap correlation

April 1, 2013
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A pictorial history of US large cap correlation

How has the distribution of correlations changed over the last several years? Previously Posts about correlation boxplots explained Data Daily returns of 443 large cap US stocks from 2004 through 2012 were used.  The sample correlations — almost 98,000 of them — during each year were created. If we were actually using the correlations, then … Continue reading →

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