Dat Ngo

LLM Observability, Evaluation, Experimentation Platform — Dat Ngo, Arize

Jun 7, 2026 · 16:32

Dat Ngo from Arize AI explains that observability and evaluation are essential for debugging nondeterministic LLM agents, where code no longer audits behavior—telemetry does. He outlines five flavors of eval signal—LLM as judge, human feedback, golden datasets, deterministic checks, and business metrics—and describes running them at different scopes: single span, multispan, trajectory, and session. Arize’s open-source Phoenix runs as a single container without Kubernetes, while the enterprise Arize AX adds Alex, an AI that scans traces for latency and errors and creates evals automatically. The goal is to automate the entire observability loop, letting developers focus on improvement rather than manual monitoring.

Engineering Better Evals: Scalable LLM Evaluation Pipelines That Work — Dat Ngo, Aman Khan, Arize

Jun 27, 2025 · 24:46

Dat Ngo, AI architect at Arize AI, presents advanced LLM evaluation strategies for production systems, arguing that effective evals go beyond out-of-the-box LLM-as-a-judge to include code-based heuristics, human feedback, and golden datasets. He explains how to build a virtuous cycle of collecting observability data, running evals, and tuning them over time, and demonstrates agent evaluation techniques like trajectory evals to identify failure modes across complex workflows. Ngo covers trade-offs between offline evals and inline guardrails, the use of log probabilities for confidence scoring, and automated prompt optimization through meta-prompting, all illustrated with customer examples from Reddit, Duolingo, and Booking.com.