For each model, we examined word-level perplexity, R@3 in next-word prediction, latency (ms/q), and energy usage (mJ/q). To explore the perplexity–recall relationship, we collected individual perplexity and recall statistics for each sentence in the test set. 
 Question: What aspects have been compared between various language models?
Quality measures using perplexity and recall, and performance measured using latency and energy usage. 