Covariance on The Standard Errorhttps://jongha-jeon-dev.github.io/standarderror/tags/covariance/Recent content in Covariance on The Standard ErrorHugo -- 0.123.7en-gbThu, 27 Aug 2026 00:00:00 +0000Linear Algebra 3: Your Covariance Matrix Is Not Positive Definitehttps://jongha-jeon-dev.github.io/standarderror/lectures/linear-algebra-3-positive-definite/Thu, 27 Aug 2026 00:00:00 +0000https://jongha-jeon-dev.github.io/standarderror/lectures/linear-algebra-3-positive-definite/Three correlations, each one a defensible estimate, each one inside [-1, 1] — and together a claim that a particular portfolio has a variance of minus 0.11.