module 2 of 7 · 40 min

Classification

Estimate class labels or probabilities and choose thresholds from real error costs.

Explain Classification clearlyImplement a small Classification exampleEvaluate whether Classification improves a simpler baselineIdentify failure cases and operational constraints
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mental model

start with the idea before the implementation.

A classifier produces evidence or probabilities and a business rule turns those into decisions.
core concepts

the mechanisms you need to reason about.

01

Probability outputs

Probability outputs is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

02

Thresholds

Thresholds is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

03

Class imbalance

Class imbalance is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

04

Calibration

Calibration is studied through intuition implementation evidence and trade-offs. The goal is to be able to explain the mechanism and verify it with a concrete test rather than only repeat a definition.

engineering lab

turn the lesson into evidence.

LAB 1

train a baseline classifier

Build the smallest version first. Record the input, expected output, measured result and one failure you discovered.

LAB 2

plot precision-recall

Build the smallest version first. Record the input, expected output, measured result and one failure you discovered.

LAB 3

choose a threshold from cost

Build the smallest version first. Record the input, expected output, measured result and one failure you discovered.

knowledge checks

prove you can explain and decide.

1

explain false positives vs false negatives

ask cortex to test me →
2

use stratified evaluation

ask cortex to test me →
3

measure calibration

ask cortex to test me →
failure modes

what usually goes wrong.

risk

accuracy-only evaluation

Detect this early by defining a baseline, a measurable signal and a condition that would cause you to stop or redesign the approach.

risk

random split on time data

Detect this early by defining a baseline, a measurable signal and a condition that would cause you to stop or redesign the approach.

risk

threshold 0.5 by habit

Detect this early by defining a baseline, a measurable signal and a condition that would cause you to stop or redesign the approach.

proof of learning

Create a short Classification engineering note with one working artifact one metric one failure case and one decision about when you would or would not use it.

Save the result in your portfolio or project repository. A strong learning artifact should make your assumptions, metrics and failure analysis visible.