Friedland chapter 13 recreation

[kennethshsu]

Summary of Changes

Friedland recreation of chapter 13

Related GitHub Issue(s)

#588

Additional Context for Reviewers

There's quite a bit of rounding errors, which I had already added to #1215

Checklist

• I passed tests locally for both code (uv run pytest) and documentation changes (uv run --directory docs jb build . --builder=custom --custom-builder=doctest)

---

Note

Low Risk
Documentation and sample-data additions only; reserving math runs through existing APIs with no apparent changes to core adjustment logic.

Overview
Adds a Friedland Chapter 13 Jupyter Book notebook that walks through Berquist–Sherman case-adequacy and disposal-rate adjustments and checks outputs against the textbook exhibits (Med Mal Exhibit I, Auto Exhibit II).

The notebook drives existing chainladder pieces—Development, DevelopmentConstant, Chainladder, and BerquistSherman—on new load_sample datasets friedland_med_mal and friedland_berq_sher_auto (registered in the data manifest). Inline assert cells reconcile triangles, LDFs/CDFs, adjusted incurred, ultimates, and IBNR to Friedland PDF pages; the author flags rounding drift vs. the text (tracked in #1215), including one CDF table that does not tie out even with rounded values.

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[github-actions]

Pyright Type Completeness

View the full pyright --verifytypes output for this commit

Project (full chainladder package, at this PR's head): 15.1% of exported symbols fully typed (208 / 1380)

	Known	Ambiguous	Unknown	Total
Project (head)	208	111	1061	1380

Other symbols referenced but not exported by chainladder: 13

	Known	Ambiguous	Unknown	Total
Other (head)	3	1	9	13

Symbols without documentation:

• Functions without docstring: 327
• Functions without default param: 0
• Classes without docstring: 10

Patch (exported symbols added or changed by this PR): no exported symbol type-completeness changes detected.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.96%. Comparing base (ba25a42) to head (b5c108e).
⚠️ Report is 56 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1327      +/-   ##
==========================================
+ Coverage   91.76%   93.96%   +2.19%     
==========================================
  Files          96       98       +2     
  Lines        5475     7784    +2309     
  Branches      706     1258     +552     
==========================================
+ Hits         5024     7314    +2290     
- Misses        327      333       +6     
- Partials      124      137      +13     

Flag	Coverage Δ
unittests	93.91% <ø> (+2.14%)	⬆️

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Stale assert column after rename

Medium Severity

The Exhibit II Sheet 4 DataFrame now stores ultimates in Projected Ultimate CLaim Counts (5), but the Friedland reconciliation still indexes Ult (5). Those asserts raise KeyError instead of checking the projected counts, so the notebook fails on execute.

 

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