AI Evaluation Strategy
Move beyond vibe checks to systematic, empirical measurement of AI product quality and reliability.
The Guide
5 key steps synthesized from 6 experts.
Conduct rigorous error analysis
Review at least 100 raw user interaction traces to categorize failures. Use open coding to group these into a prioritized taxonomy of errors, appointing a single domain expert to act as the arbiter of quality.
Featured guest perspectives
"The process that tells you where to focus is referred to as “error analysis” and should result in a clean and prioritized list of your product’s most common failure modes."— Lenny Rachitsky
"When you're doing this open coding, a lot of teams get bogged down in having a committee do this. For a lot of situations, that's wholly unnecessary. You don't want to make this process so expensive that you can't do it. You can appoint one person whose taste that you trust."— Hamel Husain & Shreya Shankar
Curate a reference golden dataset
Build a baseline set of 20 to 100 examples that represent ground truth behavior. This dataset should include the input query, the expected output, and the necessary context or metadata to ground the model.
Featured guest perspectives
"Since most products start cold, aim to gather at least 20 to 100 examples up front. This dataset helps you evaluate system performance and also tells you what context your assistant needs in order to perform reliably."— Lenny Rachitsky
"The expert’s task is to provide two things for every user interaction with your AI, grouped by session: a binary pass/fail judgment and a detailed critique."— Lenny Rachitsky
Implement the LLM-as-a-Judge playbook
Create a structured prompt for a judge LLM that defines its role and binary success criteria. Calibrate this automated judge by measuring how closely its scores align with expert human judgments on a small sample.
Featured guest perspectives
"Clearly articulating what you want your judge-LLM to measure isn’t just a step in the process; it’s the difference between a mediocre AI and one that consistently delights users. Building these writing skills requires practice and attention."— Lenny Rachitsky
"LLM-based evals allow you to generate classification labels in an automated way that resembles human-labeled data—without needing to have users or subject-matter experts label all of your data."— Lenny Rachitsky
Isolate system components for debugging
For RAG or multi-step agentic workflows, test each segment individually. Measure the retriever's recall separately from the generator's faithfulness to pinpoint exactly where technical debt or reasoning gaps exist.
Featured guest perspectives
"Evals are the only way you can break down each step in the system and measure *specifically* what impact an individual change might have on a product, giving you the data and confidence to take the right next step. Prompts may make headlines, but evals quietly decide whether your product thrives or dies."— Lenny Rachitsky
Operationalize continuous quality assurance
Integrate your most reliable evaluations into your CI/CD pipeline to act as unit tests. This ensures that every model or prompt change is automatically checked against your golden dataset to prevent regressions before shipping.
Featured guest perspectives
"Evals (short for “evaluations”) are structured ways to measure how well an AI system performs on specific tasks, such as correctness, safety, helpfulness, or tone. They define what “good” looks like for your AI system and help you answer the question: Is this model doing what I want it to do?"— Lenny Rachitsky
"In our framework, product builders work in a continuous loop of development (CD) and calibration (CC). During development, you scope the problem, design the architecture, and set up evaluations to keep non-determinism in check."— Lenny Rachitsky
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Guest Perspectives
Deep dive into what 5 podcast guests shared about ai evaluation strategy.
Aishwarya Naresh Reganti + Kiriti Badam
"It's not about being the first company to have an agent among your competitors. It's about have you built the right flywheels in place so that you can improve over time."
- Prioritize building the flywheels necessary to capture and implement improvements over time.
- Embrace the 'pain' of learning through implementation as a necessary moat against competitors.
- Adjust post-deployment lifecycles to account for the unique ways AI systems diverge from traditional software maintenance.
Brendan Foody
"I think that for enterprises especially, the core way to think about it is how can they build a test or systematic way to measure how well AI automates their core value chain? So if it's an architecture firm that's producing these architecture diagrams of what they provide to their end customer, how can they effectively measure that? And each company has its own value chain or maybe a handful of them if it's a multi-product company."
- Identify the core value chain or specific deliverables unique to your business.
- Develop systematic tests to measure how accurately AI can replicate those core outputs.
- Use custom evals as the primary requirement document for all AI initiatives.
Edwin Chen
"We are looking for a Nobel Prize-winning poetry. Is this poetry unique? Is it full of subtle imagery? Does it surprise you and target your heart? Does it teach you something about the nature of moonlight?"
- Move beyond superficial criteria like word counts or mandatory keyword presence.
- Evaluate outputs for subjective traits like subtle imagery, uniqueness, and the ability to surprise.
- Set an ambitious bar by aiming for 'Nobel Prize-winning' level human expression in training data.
"The way it works is we essentially gather thousands of signals about everything that you're doing when you're working on platform. We are looking at your keyboard strokes. We are looking how fast you answer things. We are using reviews, we are using code standards, we are using... We're training models ourselves all on the outputs that you create, and then we're seeing whether they improve the model's performance."
- Monitor granular behavioral signals like keyboard strokes and response speed to ensure human annotator engagement.
- Match evaluation tasks to annotators with specific, proven expertise in those particular domains.
- Measure progress by training internal models on human outputs to observe if they actually improve model performance.
Hamel Husain & Shreya Shankar
"Evals help you create metrics that you can use to measure how your application is doing and kind of give you a way to improve your application with confidence. That you have a feedback signal in which to iterate against."
- Create systematic metrics to track application quality over time as you change prompts or models.
- Implement simple unit tests for non-negotiable functionalities within your AI assistant.
- Track basic user signals, such as thumbs-up or thumbs-down, to create a feedback flywheel for product improvement.
"When you're doing this open coding, a lot of teams get bogged down in having a committee do this. For a lot of situations, that's wholly unnecessary. You don't want to make this process so expensive that you can't do it. You can appoint one person whose taste that you trust."
- Use 'open coding' to manually label and group raw errors into distinct failure categories.
- Assign one person whose taste you trust, often the product manager, to lead the error categorization process.
- Keep the process lightweight and inexpensive to ensure the team actually performs it regularly.
Karina Nguyen
"I think the bottleneck is actually in evaluations that we don't have all the frontier, like evals like, I don't know, GPQA, which is a Google-proof question answering, PhD level intelligence. The benchmark is getting to, I don't know, more than 60, 70%, which is what PhD gets. So it's literally hitting the wall in like evals."
- Identify the core behaviors a feature needs (e.g., when to trigger or update) to focus your evaluation efforts.
- Benchmark models against frontier datasets like GPQA to measure PhD-level intelligence.
- Use early internal dogfooding and user feedback to rapidly iterate on model performance.
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