Essays and research notes on measurement, learning science, and product.https://ssarmiento.com/enhttps://ssarmiento.com/writing/what-mastery-measurement-measures/https://ssarmiento.com/writing/what-mastery-measurement-measures/Most “mastery” dashboards measure compliance with a sequence. The difference between measuring a sequence and measuring a claim changes what you build.Fri, 12 Jun 2026 00:00:00 GMTmastery-measurementlearning-science-to-producthttps://ssarmiento.com/writing/translating-irt-for-product/https://ssarmiento.com/writing/translating-irt-for-product/Item Response Theory is not a reporting feature — it’s a way of deciding what a score is allowed to mean. Here’s the working translation for product teams.Sat, 09 May 2026 00:00:00 GMTpsychometrics-edmlearning-science-to-producthttps://ssarmiento.com/writing/bayesian-knowledge-tracing-honestly/https://ssarmiento.com/writing/bayesian-knowledge-tracing-honestly/BKT is four numbers and a strong assumption. Used honestly it’s a discipline for accumulating belief; used carelessly it launders guessing into certainty.Wed, 22 Apr 2026 00:00:00 GMTpsychometrics-edmmastery-measurement