This paper defines the measurement architecture of AIVO Meridian, a platform-specific AI brand measurement system operating across ChatGPT, Gemini, and Perplexity. Meridian is built on two complementary instruments: the Prompt Space Occupancy Score (PSOS) and the Conversational Survival Rate (CSR). PSOS measures the stability and quality of a brand's occupancy across the response space generated by AI models in purchase-intent query contexts. It operates across five dimensions: breadth, depth, resilience, sentiment, and decay. CSR measures whether a brand survives across consecutive turns within a single multi-turn AI conversation. Meridian runs four conversation types: 4-turn generic, 4-turn agentic, unlimited-turn generic, and unlimited-turn agentic. Agentic conversations name the brand as a starting anchor; the AI model then determines independently whether the brand survives to the final recommendation. We report a directional finding from live Meridian measurement: a decline in PSOS resilience for a prestige beauty brand preceded a 10-point CSR drop by one week. This observation supports the proposition that PSOS resilience functions as a leading indicator for CSR degradation. Meridian's architecture is independent of decision-stage filter methodology and constitutes a distinct measurement category from AI visibility indexing. Where visibility indexing captures presence at a point in time, PSOS measures the structural stability of that presence and CSR measures whether it survives the sequential reasoning process through which AI models generate final recommendations
AIVO Meridian (aivomeridian.com) (Sun,) studied this question.