@inproceedings{
cohen-wang2024ask,
title={Ask Your Distribution Shift if Pre-Training is Right for You},
author={Benjamin Cohen-Wang and Joshua Vendrow and Aleksander Madry},
booktitle={NeurIPS 2023 Workshop on Distribution Shifts: New Frontiers with Foundation Models},
year={2024},
url={https://openreview.net/forum?id=XQ1cGxdB3o}
}
Pre-training is a widely used approach to develop models that are robust to distribution shifts. However, in practice, its effectiveness varies: fine-tuning a pre-trained model improves robustness significantly in some cases but *not at all* in others (compared to training from scratch). In this work, we seek to characterize the failure modes that pre-training *can* and *cannot* address. In particular, we focus on two possible failure modes of models under distribution shift: poor extrapolation (e.g., they cannot generalize to a different domain) and biases in the training data (e.g., they rely on spurious features). Our study suggests that, as a rule of thumb, pre-training can help mitigate poor extrapolation but not dataset biases. After providing theoretical motivation and empirical evidence for this finding, we explore an implication for developing robust models: fine-tuning on a (very) small, non-diverse but *de-biased* dataset can result in significantly more robust models than fine-tuning on a large and diverse but biased dataset.
Ask Your Distribution Shift if Pre-Training is Right for You
Benjamin Cohen-Wang Joshua Vendrow Aleksander Madry