Posts
All the articles I've posted.
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What Decades of Marketing-Mix Data Actually Tell Us
Forty years of scanner data and split-cable experiments converge on a few numbers that are remarkably stable across brands and categories. Knowing them turns a media model from a free-for-all into something with priors.
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You Are Your Relationships: The Yoneda Lemma
Category theory's most famous lemma says something almost philosophical: an object is completely determined by its relationships to everything else. The same idea quietly powers embeddings, interfaces, and most good abstraction.
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The Effect You're Looking For Isn't in Your Panel Data
A between-person association and a within-person effect can differ in size or even flip sign. Most longitudinal models silently estimate a blend of the two, and the model you reach for decides which question you're actually answering.
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Designing Experiments to Maximize Information
There's a single objective that says what makes one experiment better than another — expected information gain. It's beautiful, it's principled, and it's a nightmare to compute. Here's the arc from Lindley in 1956 to policies that design experiments in real time.