  Transferability estimation has been attached to great attention in the
computer vision fields. Researchers try to estimate with low computational cost
the performance of a model when transferred from a source task to a given
target task. Considering the effectiveness of such estimations, the communities
of natural language processing also began to study similar problems for the
selection of pre-trained language models. However, there is a lack of a
comprehensive comparison between these estimation methods yet. Also, the
differences between vision and language scenarios make it doubtful whether
previous conclusions can be established across fields. In this paper, we first
conduct a thorough survey of existing transferability estimation methods being
able to find the most suitable model, then we conduct a detailed empirical
study for the surveyed methods based on the GLUE benchmark. From qualitative
and quantitative analyses, we demonstrate the strengths and weaknesses of
existing methods and show that H-Score generally performs well with
superiorities in effectiveness and efficiency. We also outline the difficulties
of consideration of training details, applicability to text generation, and
consistency to certain metrics which shed light on future directions.
