Model Card for Pythia-2.8B-TLDR-Iterative-SamPO

This repository provides a fine-tuned version of Pythia-2.8B, using our proposed SamPO algorithm: Eliminating Biased Length Reliance of Direct Preference Optimization via Down-Sampled KL Divergence.

Performance

vs. SFT	wins	len / token
DPO	60.98	53.8
Iterative DPO	73.58	66.65
Length Normed DPO	58.13	47.34
SimPO	33.33	31.9
Iterative SamPO	73.58	49.54

Evaluation Details

We test our model with the same GPT-4 Win rate prompt template proposed by the DPO paper. The sampled test set is included in this repo.

Training hyperparameters

The following hyperparameters were used during DPO/SamPO training:

• DPO beta: 0.5
• learning_rate: 1e-6
• total_train_batch_size: 128
• optimizer: AdamW with beta1 0.9, beta2 0.999 and epsilon 1e-8
• lr_scheduler_type: linear
• lr_scheduler_warmup_ratio: 0.1
• Weight Decay: 0.0
• num_epochs: 1.0