Evaluating Language Models as Synthetic Data Generators
Authors: name: Seungone Kim, name: Juyoung Suk, name: Xiang Yue, name: Vijay Viswanathan, name: Seongyun Lee, name: Yizhong Wang, name: Kiril Gashteovski, name: Carolin Lawrence, name: Sean Welleck, name: Graham Neubig

Given the increasing use of synthetic data in language model (LM)
post-training, an LM's ability to generate high-quality data has become nearly
as crucial as its ability to solve problems directly. While prior works have
focused on developing effective data generation methods, they lack systematic
comparison of different LMs as data generators in a unified setting. To address
this gap, we propose AgoraBench, a benchmark that provides standardized
settings and metrics to evaluate LMs' data generation abilities. Through
synthesizing 1.26 million training instances using 6 LMs and training 99
student models, we uncover key insights about LMs' data generation
capabilities. First, we observe that LMs exhibit distinct strengths. For
instance, GPT-4o excels at generating new problems, while Claude-3.5-Sonnet
performs better at enhancing existing ones. Furthermore, our analysis reveals
that an LM's data generation ability doesn't necessarily correlate with its
problem-solving ability. Instead, multiple intrinsic features of data
quality-including response quality, perplexity, and instruction
difficulty-collectively serve as better indicators. Finally, we demonstrate
that strategic choices in output format and cost-conscious model selection
significantly impact data generation effectiveness.