John Pentakalos

John Pentakalos is a Data Scientist on Glean’s Product team—an applied scientist focused on the AI Assistant and A/B testing—who turns product telemetry into clear stories marketers can use. They bring a marketer’s mindset to analytics, co-leading Assistant Metrics Reviews and introducing measurement frameworks like Growth Accounting and Incrementality Analysis to connect product signals with go‑to‑market narratives. John quantified the impact of Agentic Looping, showing 15–18% lifts in Chat DAU and a meaningful shift of queries from Search to Chat; across beta customers, they documented 80%+ increases in Chat DAU immediately post‑enrollment. They also built the Chat V2 data model that standardizes how we measure assistant engagement and feedback, and authored the Chat v1.5 experiment readout that delivered measurable latency wins without material changes to usage—work that helps product and marketing communicate real‑world value with credibility. A contributor to Glean’s Performance Benchmark blog, John consistently translates complex evaluation into customer‑friendly insights, and in their current role partners across product, data science, and marketing to help enterprises put AI to work with confidence.