Blog Archives

A weird and unintended consequence of Barr et al’s Keep It Maximal paper

January 2, 2015
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Barr et al's well-intentioned paper is starting to lead to some seriously weird behavior in psycholinguistics! As a reviewer, I'm seeing submissions where people take the following approach:1. Try to fit a "maximal" linear mixed model.  If you get...

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Should we fit maximal linear mixed models?

November 25, 2014
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Should we fit maximal linear mixed models?

Recently, Barr et al published a paper in the Journal of Memory and Language, arguing that we should fit maximal linear mixed models, i.e., fit models that have a full variance-covariance matrix specification for subject and for items. I suggest here t...

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Simulating scientists doing experiments

November 22, 2014
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Following a discussion on Gelman's blog, I was playing around with simulating scientists looking for significant effects. Suppose each of 1000 scientists run 200 experiments in their lifetime, and suppose that 20% of the experiments are such that the n...

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An adverse consequence of fitting "maximal" linear mixed models

August 23, 2014
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An adverse consequence of fitting "maximal" linear mixed models

Distribution of intercept-slope correlation estimates with 37 subjects, 15 itemsDistribution of intercept-slope correlation estimates with 50 subjects, 30 itemsShould one always fit a full variance covariance matrix (a "maximal" model) when one analyze...

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lmer vs Stan for a somewhat involved dataset.

December 17, 2013
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Here is a comparison of lmer vs Stan output on a mildly complicated dataset from a psychology expt. (Kliegl et al 2011). The data are here: https://www.dropbox.com/s/pwuz1g7rtwy17p1/KWDYZ_test.rda.The data and paper available from: http://openscience.u...

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The most common linear mixed models in psycholinguistics, using JAGS and Stan

December 16, 2013
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As part of my course in bayesian data analysis, I have put up some common linear mixed models that we fit in psycholinguistics. These are written in JAGS and Stan. Comments and suggestions for improvement are most welcome.Code: http://www.ling.uni-pots...

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New course on bayesian data analysis for psycholinguistics

October 8, 2013
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I decided to teach a basic course on bayesian data analysis with a focus on psycholinguistics. Here is the course website (below). How could this possibly be a bad idea!http://www.ling.uni-potsdam.de/~vasishth/advanceddataanalysis.html

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Linear models summary sheet

January 23, 2013
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As part of my long slog towards statistical understanding, I started making notes on the very specific topic of linear models. The details are tricky and hard to keep in mind, and it is difficult to go back and forth between books and notes to try to r...

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Review of Distance Course: Graduate Certificate in Statistics offered at Sheffield [completed: 3 June 2012]

December 1, 2011
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Recently, on Andrew Gelman's blog there was a discussion about how to get yourself a statistics education (presumably without going through the whole process of becoming a professional statistician). Here's the discussion on Gelman's blog, with lots of...

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Shravan Vasishth’s Slog (Statistics blog) 2010-10-15 06:47:00

October 15, 2010
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I foolishly tried to convert a matrix M to a vector using vector:vector(M)But this is done column wise, so that adjacent row items end up non-adjacent.The right way to do this seems to be:library(data)unmatrix(M, byrow=TRUE)

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