In general, perplexity is a measurement of how well a probability model predicts a sample. In the context of Natural Language Processing, perplexity is one way to evaluate language models.

What is NLP perplexity?

In natural language processing, perplexity is a way of evaluating language models. A language model is a probability distribution over entire sentences or texts. ... It is often possible to achieve lower perplexity on more specialized corpora, as they are more predictable.

How do you interpret perplexity?

We can interpret perplexity as the weighted branching factor. If we have a perplexity of 100, it means that whenever the model is trying to guess the next word it is as confused as if it had to pick between 100 words.