statistics

Multidimension bridge sampling (CoRe in CiRM [5])

July 13, 2010 | xi'an

Since Bayes factor approximation is one of my areas of interest, I was intrigued by Xiao-Li Meng’s comments during my poster in Benidorm that I was using the “wrong” bridge sampling estimator when trying to bridge two models of different dimensions, based on the completion (for and missing from ... [Read more...]

CoRe in CiRM [3]

July 10, 2010 | xi'an

Still drudging along preparing the new edition of Bayesian Core. I am almost done with the normal chapter, where I also changed the Monte Carlo section to include specific tools (bridge) for evidence/Bayes factor approximation. Jean-Michel has now moved to the new hierarchical model chapter and analysed longitudinal  datasets ...
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Core in CiRM [2]

July 8, 2010 | xi'an

We are making slow progress on the normal and regression chapters as we decided to write the package at the same time we revise the chapters… Jean-Michel transformed the variable selection and model choice R codes of the regression chapter into generic functions that will fit within the package. I ...
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Navigate the Bermuda Triangle of Mediation Analysis

July 6, 2010 | dan

MYTHS AND TRUTHS ABOUT AN OFTEN-USED, LITTLE-UNDERSTOOD STATISTICAL PROCEDURE If you go to a consumer research conference, you will hear tales of how experiments have undergone particular statistical rites: the attainment of the elusive crossover interaction, the demonstration of full mediation through Baron and Kenny’s sacred procedure, and so ...
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Core in CiRM [1]

July 6, 2010 | xi'an

Jean-Michel Marin and myself have thus started our “research in pair” in CIRM, Luminy, for a fortnight. We are working on the second edition of Bayesian Core and, despite working round the clock on the project (except for a one hour run around Mont Puget this morning), we are not ...
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Visualization of regression coefficients (in R)

July 2, 2010 | Tal Galili

Update (07.07.10): The function in this post has a more mature version in the “arm” package. See at the end of this post for more details. * * * * Imagine you want to give a presentation or report of your latest findings running some sort of regression analysis. How would you do it? This ... [Read more...]

The case of the missing zeroes

July 2, 2010 | David Smith

Political polling is a big industry these days, especially here in the US, and both mainstream news outlets and many of the bigger political blogs commission their own polls to measure (for example) the popularity of a sitting or candidate politician or policy. In the last week though, a very ... [Read more...]

An experiment in A/B Testing my Résumé

July 1, 2010 | Paul Butler

Objective I’ll admit it: my résumé doesn’t stand out. I’ve had some great internships, but also a tendency to work for companies that aren’t (yet!) household names. And though I’m doing fine academically, it’s not well enough to stand out … Continue reading → [Read more...]

Maps without map packages

July 1, 2010 | dan

LATITUDE + LONGITUDE + OVERPLOTTING FIX = MAPS Decision Science News is always learning stuff from colleague, physicist, mathlete, and all-around computer whiz Jake Hofman. Today, it was a quick and clean way to make nice maps in R without using any map packages: just plot the latitude and longitude of your data ... [Read more...]

Another harmonic mean approximation

June 26, 2010 | xi'an

Martin Weinberg posted on arXiv a revision of his paper, Computing the Bayesian Factor from a Markov chain Monte Carlo Simulation of the Posterior Distribution, that is submitted to Bayesian Analysis. I have already mentioned this paper in a previous post, but I remain unconvinced of the appeal of the ... [Read more...]

Do Not Log-Transform Count Data, Bitches!

June 17, 2010 | jebyrnes

OK, so, the title of this article is actually Do not log-transform count data, but, as @ascidacea mentioned, you just can’t resist adding the “bitches” to the end. Onwards. If you’re like me, when you learned experimental stats, you were taught to worship at the throne of the ...
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Stack exchange for statistical analysis needs you!

June 17, 2010 | Rob J Hyndman

The proposal to create a StackExchange site for statistical analysis is steadily moving forward. We have now completed the scoping stage which involved finding enough people willing to express an interest in the idea, and voting on some example questions to define what is allowed and what is not allowed ... [Read more...]

Conferenza a Padova

June 16, 2010 | xi'an

Today and tomorrow, I am attending the annual Italian statistical society meeting. While I appreciate very much the invitation, as well as the opportunity to walk through  Padova and Venezia for a short (and alas rainy!) hour on the way there (leaving home at 8am, walking in Venezia at noon!), ... [Read more...]

R-help follow-up: truncated exponential

June 16, 2010 | Matt Shotwell

I recently posted the message below with regard to sampling from the truncated exponential distribution. I left out the derivation of the CDF (mostly because text math is ugly), so I’ve included it here. There is also a short JSS article about truncated distributions in R. This problem in ... [Read more...]

plagiarism exposed!

June 14, 2010 | xi'an

Last morn, I had the surprise of receiving the following email: This is to inform you that the following abstract has been submitted to the 3rd International Conference of the ERCIM WG on COMPUTING & STATISTICS (ERCIM’10) Ab#: 114 Title: Goodness of Fit Via Mixtures of Beta distributions Keywords: nonparametric estimation, posterior ... [Read more...]

Stratified sampling

June 9, 2010 | xi'an

The recently arXived paper of Goldstein, Rinott and Scarsini studies the impact of refining a partition on the precision of a stratified maximising/integration Monte Carlo approach. Quite naturally, if the partition gets improved, simulating points in each set of the partition can only improve the quality of the approximation, ... [Read more...]

Go Guerrill-R on Your Data in August

June 8, 2010 | Neil Gunther

Guerrill-R, get it? Register now for the Guerrilla Data Analysis Techniques (GDAT) class to be held during the week of August 9-13, 2010. The focus will be on using R and the PDQ-R for computer performance analysis and capacity planning.(Click on the...
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biomaRt and GenomeGraphs: a worked example

June 6, 2010 | nsaunders

As promised a few posts ago, another demonstration of the excellent biomaRt package, this time in conjunction with GenomeGraphs. Here’s what we’re going to do: Grab some public microarray data Normalise and get a list of the most differentially-expressed probesets Use biomaRt to fetch the genes associated with ... [Read more...]

On particle learning

June 4, 2010 | xi'an

In connection with the Valencia 9 meeting that started yesterday, and with Hedie‘s talk there, we have posted on arXiv a set of comments on particle learning. The arXiv paper contains several discussions but they mostly focus on the inevitable degeneracy that accompanies particle systems. When Lopes et al. state ... [Read more...]
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