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Beyond Confidence: Reliable Models Should Also Consider Atypicality (NeurIPS 2023)

This is the repository for the paper Beyond Confidence: Reliable Models Should Also Consider Atypicality (NeurIPS 2023). An earlier version of the paper appeared as a Contributed Talk at ICLR 2023 Workshop on Trustworthy Machine Learning.

Overall, we demonstrate that machine learning models should also consider atypicality (i.e. how 'rare' a sample is) when making predictions. We show simple- and easy-to-implement atypicality estimators can provide significant value.

Atypicality Estimation

LLM CLassification

For large language models, the log-likelihood provided by the model already estimates how typical a prompt is. Therefore, we simply use

from model_zoo import get_alpaca7b
# Assume we have the path to Alpaca7B under `model_path`
model = get_alpaca7b(model_path=model_path)
test_atypicality = -model.get_batch_loglikelihood(test_prompts)

We will later use the atypicality value in the recalibration algorithm to boost accuracy and calibration. See model_zoo/llm.py for further details.

Obtaining Alpaca7b: Please refer to https://github.com/tatsu-lab/stanford_alpaca for instructions on how to obtain Alpaca7b.

Image Classification

For image classifiers, there is no out-of-the-box atypicality estimator. Therefore, we use the following simple estimator:

from atypicality import GMMAtypicalityEstimator
from model_zoo import get_image_classifier
from data_zoo import get_image_dataset

# First, load the dataset and model of interest.
model, preprocess = get_image_classifier("resnext50_imagenet_lt", device="cuda")
train_dataset, val_dataset, test_dataset = get_image_dataset("imagenet_lt", preprocess=preprocess)
# We first extract the features for the training and test sets:
train_features, train_logits, train_labels = model.run_and_cache_outputs(train_dataset, batch_size=16, output_dir="./outputs/")
calib_features, calib_logits, calib_labels = model.run_and_cache_outputs(val_dataset, batch_size=16, output_dir="./outputs/")
test_features, test_logits, test_labels = model.run_and_cache_outputs(test_dataset, batch_size=16, output_dir="./outputs/")
# Then, we fit the estimator to the embeddings of the training set:
atypicality_estimator = GMMAtypicalityEstimator()
atypicality_estimator.fit(train_features, train_labels)
# We then use the estimator to estimate atypicality of the calibration and test sets:
calib_atypicality = atypicality_estimator.predict(calib_features)
test_atypicality = atypicality_estimator.predict(test_features)

Improving Calibration (and Performance) with Atypicality-Aware Recalibration (AAR)

Once the atypicality of different inputs are computed, we can perform atypicality-aware recalibration with a few simple lines:

from calibration import AtypicalityAwareCalibrator
aar_calib = AtypicalityAwareCalibrator()
# Train the AAR calibrator: 
aar_calib.fit(calib_logits, calib_atypicality, calib_labels, max_iters=1500)
# Use the AAR calibrator:
test_pred_probs = aar_calib.predict_proba(test_logits, test_atypicality)

Reproducing Results

To reproduce our LLM classification experiments, please refer LLM Classification.ipynb.

Similarly, to reproduce our image classification experiments, please refer to Imbalanced Image Classification.ipynb and Balanced Image Classification.ipynb.

In each of the above notebooks, we demonstrate how atypicality-awareness improves the accuracy and the calibration of the models.

Citation

If you find this repository or the ideas therein useful, please consider citing our paper:

@article{yuksekgonul2023beyond,
  title={Beyond Confidence: Reliable Models Should Also Consider Atypicality},
  author={Yuksekgonul, Mert and Zhang, Linjun and Zou, James and Guestrin, Carlos},
  journal={arXiv preprint arXiv:2305.18262},
  year={2023}
}