Definition

Head term

A head term is a broad, high-demand query such as 'best CRM'. In AI answers these are the most contested and the least reproducible prompts.

Short prompts show meaningfully more citation volatility than long ones, so head terms need deeper sampling to reach the same interval width.

They are still worth tracking because they set category perception, but they should be reported with wider intervals and more caution.

Related terms

Long-tail query Prompt set Citation volatility

Nostimates measures head term across twelve AI answer surfaces. Request access →

All terms

AEO (Answer Engine Optimisation)GEO (Generative Engine Optimisation)AI Overviews AI Mode Citation share n-sampling Query fan-out Grounding Share of voice (AI)Extraction success rate Surface Answer engine Citation Brand mention Mention rate Confidence interval Statistical significance Citation volatility Non-determinism Reproducibility Identity-free collection Personalisation Locale Residential proxy Bot detection Collection cost Credit Evidence retention Audit trail Parser version Canary prompt Data freshness Cadence Prompt set Long-tail query Competitive set llms.txt robots.txt AI crawler Training crawler Retrieval-augmented generation (RAG)Hallucination Answer box Featured snippet Zero-click search Entity Entity salience Knowledge graph Structured data JSON-LD schema.org FAQ schema Answer-first content Chunk Embedding Semantic search Prompt injection Market coverage Sentiment analysis Position tracking White-label data