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Module 09 · Evals

Building AI you can trust

A demo is not a system.

What you’ll learn

Four ideas, one module

01

Golden sets

A small, versioned set of real cases that defines “working”.

02

Three ways to grade

Deterministic checks, human review and LLM judges, and when to use each.

03

Failures and regressions

Name the failure type, then rerun the set on every change.

04

Quality, cost, latency

Choose what belongs in production, not what won the demo.

Applied exercise

Better, slower, pricier

Compare two architectures where one performs better but is substantially slower and more expensive. Decide what belongs in production.

  • Architecture A
  • Architecture B
  • The decision

Cheat sheet

If you can’t name the number that would make you roll back, you don’t know it works

One page you keep: the questions to ask on every project, the rules of thumb, and a template you can use on your own product. All ten come with The Book.

Leave at the door

Five myths this module breaks

MythWhat’s actually true
“LLM-as-a-judge is objective.”It has biases. Calibrate it against human labels.
“I tried it a few times. It works.”A few tries are anecdotes. Use a golden set.
“One accuracy number tells the story.”Break failures down by type and by cost.
“The best model belongs in production.”The best fit for quality, cost and latency does.
“Evals are a launch step.”Rerun them on every prompt, model or data change.

Before you move on

Can you call this one?

After a model upgrade, users say the assistant “got worse”.

What would you need in place to confirm or refute it in an hour? Name three pieces.

Portrait of Remy Calder

The Benchmark Saboteur

Remy Calder

stress-tests the tests themselves, exposing impressive scores that hide embarrassing failures.

Episode 09 · Building AI you can trust

Included with the course.

Coming soon · an AI character from the show, not a real researcher.