Good eye/mind catches logical fallacy in WSJ Analysis

Jean Whit notes that the authors of this piece about Wall Street Journal number crunching about sovereign debt default and bond ratings, WSJ Analysis: Rating Firms Not Effective at Predicting Government Defaults, got their analysis backwards. A classic case of sampling on the dependent variable or percentaging in the wrong direction: how many of the defaults had a given rating rather than how many with a given rating end up defaulting. See Jean’s comment at bottom of post.

Author: Dan Ryan

I'm currently an Academic Program Director at I've been a professor at University of Toronto, University of Southern California, and Mills College teaching things like human centered design, computational thinking, modeling for policy sciences, and social theory. I'm driven by the desire to figure out how to teach twice as many twice as well twice as easily.

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