Search Results for author: William T. Stephenson

Found 7 papers, 3 papers with code

Can we globally optimize cross-validation loss? Quasiconvexity in ridge regression

no code implementations NeurIPS 2021 William T. Stephenson, Zachary Frangella, Madeleine Udell, Tamara Broderick

In the present paper, we show that, in the case of ridge regression, the CV loss may fail to be quasiconvex and thus may have multiple local optima.

regression

Measuring the robustness of Gaussian processes to kernel choice

no code implementations11 Jun 2021 William T. Stephenson, Soumya Ghosh, Tin D. Nguyen, Mikhail Yurochkin, Sameer K. Deshpande, Tamara Broderick

We demonstrate in both synthetic and real-world examples that decisions made with a GP can exhibit non-robustness to kernel choice, even when prior draws are qualitatively interchangeable to a user.

Gaussian Processes

Approximate Cross-Validation with Low-Rank Data in High Dimensions

no code implementations NeurIPS 2020 William T. Stephenson, Madeleine Udell, Tamara Broderick

Our second key insight is that, in the presence of ALR data, error in existing ACV methods roughly grows with the (approximate, low) rank rather than with the (full, high) dimension.

Vocal Bursts Intensity Prediction

Approximate Cross-Validation for Structured Models

1 code implementation NeurIPS 2020 Soumya Ghosh, William T. Stephenson, Tin D. Nguyen, Sameer K. Deshpande, Tamara Broderick

But this existing ACV work is restricted to simpler models by the assumptions that (i) data across CV folds are independent and (ii) an exact initial model fit is available.

Sentence

Approximate Cross-Validation in High Dimensions with Guarantees

1 code implementation31 May 2019 William T. Stephenson, Tamara Broderick

Crucially, though, we are able to show, both empirically and theoretically, that one approximation can perform well in high dimensions -- in cases where the high-dimensional parameter exhibits sparsity.

Vocal Bursts Intensity Prediction

Reconstructing probabilistic trees of cellular differentiation from single-cell RNA-seq data

no code implementations28 Nov 2018 Miriam Shiffman, William T. Stephenson, Geoffrey Schiebinger, Jonathan Huggins, Trevor Campbell, Aviv Regev, Tamara Broderick

Specifically, we extend the framework of the classical Dirichlet diffusion tree to simultaneously infer branch topology and latent cell states along continuous trajectories over the full tree.

Scalable Adaptation of State Complexity for Nonparametric Hidden Markov Models

1 code implementation NeurIPS 2015 Michael C. Hughes, William T. Stephenson, Erik Sudderth

Bayesian nonparametric hidden Markov models are typically learned via fixed truncations of the infinite state space or local Monte Carlo proposals that make small changes to the state space.

speaker-diarization Speaker Diarization

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