A live worked example you can take apart: the bound 2026 year next to the 2027 ask. Renewal reading is differential reading — the absolute numbers matter less than what moved, and the product stores both vintages as separate submission nodes precisely so you can diff them (2026 · 2027).
What moved, per the cell below:
- Layer 1 7m xs 3m: rate on line 7.5% → 7.8% — +4.0%.
- Layer 2 15m xs 10m: rate on line 3.2% → 3.4% — +6.25%.
- Subject premium 120m → 127.5m — +6.25% portfolio growth.
- Stated loss ratio 0.68 → 0.72 — the claims year Part 2 of this course dissects.
This copy is yours to tinker with. Set Layer 2's 2027 rate back to 0.032 and re-run: the rate change collapses to 0 while Layer 1 still shows +4.0% — the diff is per layer, never one blended number.
Compare Alpina MTPL XL 2026 (bound: L1 7m xs 3m at 7.5%, L2 15m xs 10m at 3.2%, subject premium 120m, LR 0.68) with the 2027 renewal (L1 at 7.8%, L2 at 3.4%, subject premium 127.5m, LR 0.72): a grid with one row per layer and vintage columns, the rate change per layer, and totals showing premium at 100% moving 1,005,000 → 1,056,000.
When you can read the diff, go test yourself on the Lesson 1 exercises.