metrics, slices, and error analysis

Model quality is not a single number. This chapter turns confusion matrices, precision, recall, thresholds, slices, residuals, and triage notes into evidence a teammate can inspect.

The exercises use small Python dictionaries and lists so every check can run in the browser. Real-world tools may be larger, but the review shape stays the same: input, decision, evidence, blocker, and next step.

By the end of the chapter, learners should be able to turn this topic into a concrete handoff instead of a vague model claim.