Another Brief Test of Your Bayesian Intuition: The Answer

In a previous blog post, we proposed the following test of your Bayesian intuition: Three friends –Alex, Bart, and Cedric– each assign their own prior distribution to a binomial chance parameter θ. Let’s say that θ is the chance that Harriet bakes a vegan pancake rather than a bacon pancake. Alex assigns θ a beta(300,3) prior distribution, indicating a strong…

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Another Brief Test of Your Bayesian Intuition

Three friends –Alex, Bart, and Cedric– each assign their own prior distribution to a binomial chance parameter θ. Let’s say that θ is the chance that Harriet bakes a vegan pancake rather than a bacon pancake. Alex assigns θ a beta(300,3) prior distribution, indicating a strong belief in high values of θ (i.e., Alex predicts that almost all of Harriet’s…

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How to Memorize Bayes’ Rule

Bayes’ rule dictates how new data update the credibility of competing accounts of the world . An immediate consequence of the definition of conditional probability, Bayes’ rule is usually presented as follows: The way I mentally check this equation is to take the denominator of the expression on the right-hand side, , and multiply it with the left side of…

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A Good Check on the Bayes Factor

As regular readers of this blog already know, Bayes factors rule! In practice, however, the calculation of Bayes factors is seriously hampered by computational difficulties. In a new paper, we revive two theorems put forth by Alan Turing and Jack Good and propose a step-by-step approach to use them as a check for the calculation of Bayes factors. According to…

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The University of Amsterdam Bans The Teaching of P-Values

I am thrilled to report that, after considerable discussion, the University of Amsterdam has agreed to ban the teaching of p-values for first-year students at the Faculty of Social and Behavioural Sciences. The new policy will take effect at the start of the new academic year, and its introduction was facilitated by the fact that I am taking over from…

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Classroom Demonstration of Ockham’s Razor with Polyhedral Dice

Inspired by a recent article on Ockham’s razor, this post shows how a simple set of polyhedral dice can clarify the basic idea underlying Bayes factors (or likelihood ratios).  The ideas may be used in a classroom demonstration, and each of the lessons below could be discovered by the students themselves. Meet the Family Our polyhedral dice are a family…

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Does Statistical Amateurism Cause Questionable Research Practices? Book Review of “Never Waste a Good Crisis”

Klaas Sijtsma is an experienced psychometrician and former rector magnificus of Tilburg University. In “Never waste a good crisis”, Sijtsma discusses academic fraud (and in particular the infamous Stapel case, the fallout of which he had to deal with as dean of the School of Social and Behavioral Sciences at Tilburg University) and questionable research practices (henceforth QRPs). Importantly, Sijtsma…

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