PPL

PPL, or Perplexity, is a measurement used to evaluate how well a language model predicts a piece of text. It indicates the model's uncertainty: lower PPL means the model is more confident and accurate in predicting words, while higher PPL suggests less confidence. Think of it as a way to gauge how "surprised" the model is by the text. For example, if a model has low perplexity on a sentence, it means the sentence contains predictable language that the model understands well. It’s a useful metric for assessing and comparing the performance of different language models.