1. A team is setting up LLM-as-judge evaluations to score the quality of chatbot responses on a scale of 1–5. A senior researcher raises the concern of 'position bias.' What does position bias refer to in this context?
- A. The judge LLM tends to give higher scores to shorter responses regardless of their quality
- B. The judge LLM's score is influenced by whether the evaluated response appears first or second in a pairwise comparison, rather than purely on quality✓ Correct
- C. The judge LLM systematically rates responses on topics outside its training distribution lower than warranted
- D. The judge LLM inflates scores for responses that include confident, assertive language
Explanation
Position bias in LLM-as-judge refers to the tendency of a judge model to favor responses based on their position in a prompt (e.g., preferring the first option in a pairwise comparison) rather than their actual quality. This is a well-documented failure mode. Option A describes verbosity bias (or the inverse, brevity bias), which is a different known bias. Option C describes a domain coverage issue, not a position-related bias. Option D describes a confidence or style bias, not position bias.