Michael Oberst
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moberst.bsky.social
Michael Oberst
@moberst.bsky.social
Assistant Prof. of CS at Johns Hopkins
Visiting Scientist at Abridge AI
Causality & Machine Learning in Healthcare
Prev: PhD at MIT, Postdoc at CMU
To capture these challenges, we assume that model impact is mediated by both the output of the model (A), and the performance characteristics (M).

This formalism allows us to start reasoning about the impact of new models with different outputs and performance characteristics.
July 23, 2025 at 2:10 PM
The second challenge is trust: Impact depends on the actions of human decision-makers, and those decision-makers may treat two models differently based on their performance characteristics (e.g., if a model produces a lot of false alarms, clinicians may ignore the outputs).
July 23, 2025 at 2:10 PM
We tackle two non-standard challenges that arise in this setting, *coverage* and *trust*.

The first challenge is coverage: If the new model is very different from previous models, it may produce outputs (for specific types of inputs) that were never observed in the trial.
July 23, 2025 at 2:10 PM
We develop a method for placing bounds on the impact of a *new* ML model, by re-using data from an RCT that did not include the model.

These bounds require some mild assumptions, but those assumptions can be tested in practice using RCT data that includes multiple models.
July 23, 2025 at 2:10 PM
Randomized trials (RCTs) help evaluate if deploying AI/ML systems actually improves outcomes (e.g., survival rates in a healthcare context).

But AI/ML systems can change: Do we need a new RCT every time we update the model? Not necessarily, as we show in our UAI paper! arxiv.org/abs/2502.09467
July 23, 2025 at 2:10 PM
I'm recruiting PhD students for Fall 2025! CS PhD Deadline: Dec. 15th.

I work on safe/reliable ML and causal inference, motivated by healthcare applications.

Beyond myself, Johns Hopkins has a rich community of folks doing similar work. Come join us!
November 27, 2024 at 3:58 PM