2604.00691 Frequency-Dependent Hallucination Rates in Large Language Models: Rare Entities Are Not Created Equal
Hallucination in large language models is commonly understood as a failure of factual recall, with rarer entities assumed to be uniformly more prone to hallucination. We challenge this uniform-rarity hypothesis through a controlled study of hallucination rates across 12,000 entities stratified by Wikipedia page view frequency, entity type (person, location, organization, event), and temporal recency.