Friedland Chapter 15 - Evaluation of Techniques (comparison tables) by EKtheSage · Pull Request #1220 · casact/chainladder-python

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

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henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

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henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

EKtheSage · 2026-08-16T09:26:08Z

Summary

Recreate the Chapter 15 U.S. Industry Auto and changing-conditions IBNR comparison tables in docs/friedland/chapter_15.ipynb.
Reuse the Chapter 7-10 development selections, expected claim ratios, and BF / Cape Cod / Benktander setups, and assert against Friedland's printed totals.
XYZ Exhibit I, Berquist-Sherman summaries, and DC Insurer monitoring are left for a later slice (they depend on Chapters 11-13).

Related to #588.

Test plan

pytest --nbmake docs/friedland/chapter_15.ipynb
Confirm the Industry Auto table rounds to the printed billions (26/71, 29/74, 26/71, 26/71, 27/73, 27/73)
Confirm the Increasing Claim Ratios column matches; remaining columns stay within the documented sample tolerance

Made with Cursor

Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-08-16T09:27:01Z

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 (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

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: 323
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 · 2026-08-16T09:32:40Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (606be5c) to head (f277acc).

Additional details and impacted files

@@ Coverage Diff @@## main #1220 +/- ##
=======================================
Coverage 91.27% 91.27% =======================================
Files 91 91 Lines 5411 5411 Branches 692 692 =======================================
Hits 4939 4939 Misses 338 338 Partials 134 134

Flag	Coverage Δ
unittests	`91.27% <ø> (ø)`

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

henrydingliu · 2026-08-16T17:12:42Z

for chapter 15, we should try to persist previous chapters' estimates without re-calculation. could you please go back to chapter 7-10, add to_json where applicable, and pick up the estimates directly in chapter 15?

EKtheSage · 2026-08-16T23:48:49Z

The to_json / read_json path is the right one — Chapter 9 and 10 already load the Chapter 7 XYZ selected development that way.

This slice cannot do the same yet. The only persisted Friedland estimators are friedland_ch7_xyz_reported.json and friedland_ch7_xyz_paid.json. The Chapter 15 comparison tables use U.S. Industry Auto, the U.S. PP Auto changing-conditions scenarios, and the product-mix portfolio. Chapters 7–10 do not currently write those fitted estimators (development selections, expected claims, BF, Cape Cod, Benktander) to JSON.

Once those chapters persist the relevant objects, Chapter 15 can read_json them instead of refitting. In the meantime we will work on Exhibit IV (DC Insurer actual-vs-expected monitoring), which does not depend on those files.

EKtheSage · 2026-08-18T00:50:21Z

Parallel bite-sized slice (Exhibit IV monitoring, no Ch 7-10 JSON dependency): #1224

docs: add Friedland Chapter 15 comparison tables
f277acc
Recreate the Industry Auto and changing-conditions IBNR summaries from the text. Co-authored-by: Cursor <cursoragent@cursor.com>

EKtheSage requested review from genedan, henrydingliu, jbogaardt and kennethshsu as code owners August 16, 2026 09:26

EKtheSage mentioned this pull request Aug 16, 2026
Reconcile data against Friedland's text used in Exam 5 #588
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EKtheSage mentioned this pull request Aug 18, 2026
Friedland Chapter 15 - DC Insurer monitoring (Exhibit IV) #1224
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