Raj Movva

@rajmovva.bsky.social

NLP, ML & society, healthcare. PhD student at Berkeley, previously CS at MIT. https://rajivmovva.com/

We made traversle.io, a new daily word game! The goal is to traverse from a start word to a target word through a network of related words. (Our motivating question: is it possible to construct a network that allows human navigation?)

New paper! The Linear Representation Hypothesis is a powerful intuition for how language models work, but lacks formalization. We give a mathematical framework in which we can ask and answer a basic question: how many features can be stored under the hypothesis? 🧵 arxiv.org/abs/2602.11246

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New #NeurIPS2025 paper: how should we evaluate machine learning models without a large, labeled dataset? We introduce Semi-Supervised Model Evaluation (SSME), which uses labeled and unlabeled data to estimate performance! We find SSME is far more accurate than standard methods.

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I am on the job market this year! My research advances methods for reliable machine learning from real-world data, with a focus on healthcare. Happy to chat if this is of interest to you or your department/team.

I've been working for many months on this article on Silicon Valley's under-the-radar role in bringing AI into schools across the US. I really hope you'll read it — here's a gift link — but I'll tell you some of the highlights in this thread. (1/x)

How Chatbots and AI Are Already Transforming Kids' Classrooms

Educators across the country are bringing chatbots into their lesson plans. Will it help kids learn or is it just another doomed ed-tech fad?

bloomberg.com

🚨 New postdoc position in our lab at Berkeley EECS! 🚨 (please reshare) We seek applicants with experience in language modeling who are excited about high-impact applications in the health and social sciences! More info in thread 1/3

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This is great, & there's clear analogy to the burgeoning mechanism design community for AI alignment: who is providing RLHF votes? Do their preferences reflect yours? Discussions about social choice and collective constitutions are interesting, but "what and who is in the data" is just as important.

Nikhil Garg@nkgarg.bsky.social · 12mo ago

New piece, out in the Sigecom Exchanges! It's my first solo-author piece, and the closest thing I've written to being my "manifesto." #econsky #ecsky arxiv.org/abs/2507.03600

Screenshot of paper abstract, with text: "A core ethos of the Economics and Computation (EconCS) community is that people have complex private preferences and information of which the central planner is unaware, but which an appropriately designed mechanism can uncover to improve collective decisionmaking. This ethos underlies the community’s largest deployed success stories, from stable matching systems to participatory budgeting. I ask: is this choice and information aggregation “worth it”? In particular, I discuss how such systems induce heterogeneous participation: those already relatively advantaged are, empirically, more able to pay time costs and navigate administrative burdens imposed by the mechanisms. I draw on three case studies, including my own work – complex democratic mechanisms, resident crowdsourcing, and school matching. I end with lessons for practice and research, challenging the community to help reduce participation heterogeneity and design and deploy mechanisms that meet a “best of both worlds” north star: use preferences and information from those who choose to participate, but provide a “sufficient” quality of service to those who do not."

📢New POSITION PAPER: Use Sparse Autoencoders to Discover Unknown Concepts, Not to Act on Known Concepts Despite recent results, SAEs aren't dead! They can still be useful to mech interp, and also much more broadly: across FAccT, computational social science, and ML4H. 🧵

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New work 🎉: conformal classifiers return sets of classes for each example, with a probabilistic guarantee the true class is included. But these sets can be too large to be useful. In our #CVPR2025 paper, we propose a method to make them more compact without sacrificing coverage.

A gif explaining the value of test-time augmentation to conformal classification. The video begins with an illustration of TTA reducing the size of the  predicted set of classes for a dog image, and goes on to explain that this is because TTA promotes the true class's predicted probability to be higher, even when it's predicted to be unlikely.

I would like to spend up to 5-10 hours to learn about basic macroeconomics (I know it's maybe fake, but setting that aside for a moment...). Does anyone have any recommendations?

People love to hate on the transition 3-pointer as evidence of how the 3 has ruined basketball, but I think it's usually just the right play... if you have numbers in transition, your teammate can easily get a putback off a miss, so might as well try the 3

Check out Erica's nice work. They not only develop a well-grounded model for disparities in disease progression, but also conduct experiments with real NYP cardiology data! (Anyone who works in healthcare knows how much of a feat it is to use data other than MIMIC)

Erica Chiang@ericachiang.bsky.social · last yr.

I’m really excited to share the first paper of my PhD, “Learning Disease Progression Models That Capture Health Disparities” (accepted at #CHIL2025)! ✨ 1/ 📄: arxiv.org/abs/2412.16406

The US government recently flagged my scientific grant in its "woke DEI database". Many people have asked me what I will do. My answer today in Nature. We will not be cowed. We will keep using AI to build a fairer, healthier world. www.nature.com/articles/d41...

My ‘woke DEI’ grant has been flagged for scrutiny. Where do I go from here?

My work in making artificial intelligence fair has been noticed by US officials intent on ending ‘class warfare propaganda’.

nature.com

1st post on bsky! What happens when a static benchmark comes to life? ✨ Introducing ChatBench, a large-scale user study where we *converted* MMLU questions into thousands of user-AI conversations. Then, we trained a user simulator on ChatBench to generate user-AI outcomes on unseen questions. 1/ 🧵

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A weird (and seemingly fixable quirk) with ChatGPT Deep Research is hallucinations even when there is a linked citation with a highlighted passage: "X et al find Y (arXiv link)" and you click on the arXiv link, which is neither written by X nor do they find Y...

Migration data lets us study responses to environmental disasters, social change patterns, policy impacts, etc. But public data is too coarse, obscuring these important phenomena! We build MIGRATE: a dataset of yearly flows between 47 billion pairs of US Census Block Groups. 1/5

I've learned MCMC 5+ different times in the last 10 years from courses, videos, blogposts, etc, and it never clicked. 30 minutes chatting with Claude this morning, and I finally feel like I've figured it out...

💡New preprint & Python package: We use sparse autoencoders to generate hypotheses from large text datasets. Our method, HypotheSAEs, produces interpretable text features that predict a target variable, e.g. features in news headlines that predict engagement. 🧵1/