Perplexity is calculated based on the cross-entropy measure of a model's predictions. The formula is complex, but simply put, a model's perplexity (PP) can be expressed like so:
In the scope of AI, particularly with chatbots and other conversational agents, perplexity plays a significant role in ensuring that the generated content is not only coherent but also contextually relevant. Models like
GPT (Generative Pre-trained Transformer) and others evaluate perplexity to improve their performance, fine-tuning their word predictions based on feedback from this metric (
Wikipedia).