Blog Archives

A simple proof that the p-value distribution is uniform when the null hypothesis is true

April 20, 2016
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Someone asked this question in my linear modeling class: why is it that the p-value has a uniform distribution when the null hypothesis is true? Proof is remarkably simple.First, notice that when a random variable Z comes from a \$Uniform(0,1)\$ distribu...

Automating R exercises and exams using the exams package

January 17, 2016
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It's a pain to design statistics exercises each semester, and because students from previous share old exercises with the new incoming students, it's hard to design simple exercises that students haven't already seen the answers to. On top of that, som...

My MSc thesis: A meta-analysis of relative clause processing in Mandarin Chinese using bias modelling

January 6, 2016
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Here is my MSc thesis, which was submitted to the University of Sheffield in September 2015. The pdf is here.Title: A Meta-analysis of Relative Clause Processing in Mandarin Chinese using Bias Modelling AbstractThe reading difficulty associated wi...

Some reflections on teaching frequentist statistics at ESSLLI 2015

August 17, 2015
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I spent the last two weeks teaching frequentist and Bayesian statistics at the European Summer School in Logic, Language, and Information (ESSLLI) in Barcelona, at the beautiful and centrally located Pompeu Fabra University. The course web page for the first week is here, and the web page for the second course is here. (NOTE: Uni Potsdam...

Getting a statistics education: Review of the MSc in Statistics (Sheffield)

February 14, 2015
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Some background:I started using statistics for my research sometime in 1999 or 2000. I was a student at Ohio State, Linguistics, and I had just gotten interested in psycholinguistics. I knew almost nothing ...

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...

Should we fit maximal linear mixed models?

November 25, 2014
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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...

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...

An adverse consequence of fitting "maximal" linear mixed models

August 23, 2014
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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...

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...