HC3 Human vs. ChatGPT Detector (HW1)

Fine-tuned hc3-finetuned to classify answers from the HC3 dataset as human (label 0) or ChatGPT (label 1).

Results (test set, 4,668 examples, balanced)

Model Test accuracy
Baseline: frozen sentence embeddings + logistic regression 0.8449 (84.49%)
Fine-tuned transformer (this model) 0.9754 (97.54%)

Fine-tuned confusion matrix: all 2,334 ChatGPT answers were correctly detected; 115 of 2,334 human answers were misclassified as ChatGPT (all errors are false positives on human text).

Training setup

  • Full fine-tuning, 5 epochs, AdamW, constant learning rate, no validation-based early stopping.

Limitations

  • Trained and tested only on HC3 (ChatGPT, late 2022). Expect lower accuracy on other domains, newer models, or edited/paraphrased AI text.
  • Errors are skewed toward flagging formal human writing as AI. Do not use this model to make decisions about individuals.

Usage

from transformers import pipeline
clf = pipeline("text-classification", model="dsantra2/hw1-hc3-detector")
clf("Your text here")
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Dataset used to train dsantra2/hw1-hc3-detector