  Semantic consistency of a language model is broadly defined as the model's
ability to produce semantically-equivalent outputs, given
semantically-equivalent inputs. We address the task of assessing
question-answering (QA) semantic consistency of contemporary large language
models (LLMs) by manually creating a benchmark dataset with high-quality
paraphrases for factual questions, and release the dataset to the community.
  We further combine the semantic consistency metric with additional
measurements suggested in prior work as correlating with LLM QA accuracy, for
building and evaluating a framework for factual QA reference-less performance
prediction -- predicting the likelihood of a language model to accurately
answer a question. Evaluating the framework on five contemporary LLMs, we
demonstrate encouraging, significantly outperforming baselines, results.
