Lesson 1: Fair and explained: who the model fails, and why
29 min read·
Module 14 · Lesson 1 · About 55 minutes · Needs: model v2 and error analysis (Module 6 lesson 2), the warning threshold and costs (Module 3 lesson 3), and the Kestrel data (course-guide/06).
The situation
Week 14 at Kestrel. Hannah forwards two emails: a customer on an island route asks why she is warned so often, and a local councillor asks whether the model treats island customers worse. Adaeze wants both answered with numbers.
One parcel runs through the lesson: KP0088193 (simulated), on island route INV-R09, handed in on Monday 24 August 2026 at 18:00 for next-day delivery, with a new driver. Model v2 gives it 0.231, above the 0.129 threshold, so its customer was warned. It was late.