Xiang ShiI'm Xiang. I build risk models at a hedge fund and write code for fun. This is where I keep my open-source code, math notes, and the occasional essay.https://xshi19.github.io/enHarari’s Imagined Imagined Communitieshttps://xshi19.github.io/harari-imagined-communities.htmlhttps://xshi19.github.io/harari-imagined-communities.htmlA critique of Harari’s account of shared stories and large-scale cooperation.Fri, 04 Sep 2026 01:37:32 GMTinformationsurvivorship biasCommon Arguments About the AI Bubblehttps://xshi19.github.io/ai-bubble-arguments.htmlhttps://xshi19.github.io/ai-bubble-arguments.htmlFive common AI bubble arguments, from valuations to workplace productivity.Wed, 18 Feb 2026 04:05:30 GMTmachine learningeconomicsSupervised Learning, RLHF, and DeepSeek R1https://xshi19.github.io/supervised-learning-rlhf-deepseek-r1.htmlhttps://xshi19.github.io/supervised-learning-rlhf-deepseek-r1.htmlA math-class analogy for how three training approaches score an LLM’s answers.Wed, 12 Feb 2025 01:38:06 GMTmachine learningA Simple Stock Market Trick: Use Logarithmic Chartshttps://xshi19.github.io/use-logarithmic-charts.htmlhttps://xshi19.github.io/use-logarithmic-charts.htmlWhy logarithmic stock charts make percentage changes easier to compare.Wed, 20 Nov 2024 03:04:53 GMTeconomicsFarewell, Yann LeCunhttps://xshi19.github.io/farewell-yann-lecun.htmlhttps://xshi19.github.io/farewell-yann-lecun.htmlOn Yann LeCun, scientific metrics, and having skin in the game.Wed, 13 Nov 2024 04:15:21 GMTmachine learningeconomicsYuval Harari's Dataism: Why is it a Bad Idea?https://xshi19.github.io/yuval-hararis-dataism-why-is-it-a-bad-idea.htmlhttps://xshi19.github.io/yuval-hararis-dataism-why-is-it-a-bad-idea.htmlWhy more connections and more data do not necessarily mean more information.Sat, 17 Feb 2024 05:00:00 GMTdataisminformationdata scienceEstimate Book Review Entropy from Pre-trained Embeddingshttps://xshi19.github.io/estimate-book-review-entropy-from-pre-trained-embeddings.htmlhttps://xshi19.github.io/estimate-book-review-entropy-from-pre-trained-embeddings.htmlAn experiment in measuring the diversity of book reviews with embeddings and entropy.Mon, 25 Dec 2023 05:00:00 GMTNLPmachine learninginformation theoryA Simple Way to Estimate DDP, A Better Alternative to GDPhttps://xshi19.github.io/a-simple-way-to-estimate-ddp-a-better-alternative-to-gdp.htmlhttps://xshi19.github.io/a-simple-way-to-estimate-ddp-a-better-alternative-to-gdp.htmlEstimating Democratic Domestic Product with the Gini index and a Pareto distribution.Thu, 21 Dec 2023 05:00:00 GMTfat tailseconomicsFat Tails, Survivorship Bias, and the Illusion of Exponential Growthhttps://xshi19.github.io/fat-tails-survivorship-bias-and-the-illusion-of-exponential-growth.htmlhttps://xshi19.github.io/fat-tails-survivorship-bias-and-the-illusion-of-exponential-growth.htmlHow focusing on the winners can turn fat-tailed outcomes into a story of exponential growth.Thu, 07 Dec 2023 15:20:00 GMTfat tailssurvivorship biaspersonal development