From fb34a160b4b24d520455dadffa1b7962980080a8 Mon Sep 17 00:00:00 2001
From: Ethan Kang <ethan.yskang@gmail.com>
Date: Sat, 16 May 2026 01:17:52 -0700
Subject: [PATCH 1/2] docs: add ClarkLDF doctest examples

---
 chainladder/development/clark.py | 52 ++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/chainladder/development/clark.py b/chainladder/development/clark.py
index f8e1db17..c2641e82 100644
--- a/chainladder/development/clark.py
+++ b/chainladder/development/clark.py
@@ -54,6 +54,58 @@ class ClarkLDF(DevelopmentBase):
     norm_resid_: Triangle
         The "Normalized" Residuals of the model according to Clark.
 
+    Examples
+    --------
+    ``growth`` selects the incremental curve; the first LDF cell moves slightly
+    between ``loglogistic`` (default) and ``weibull``.
+
+    .. testsetup::
+
+        import chainladder as cl
+
+    .. testcode::
+
+        import numpy as np
+
+        tri = cl.load_sample("ukmotor")
+        m_log = cl.ClarkLDF(growth="loglogistic").fit(tri)
+        m_wei = cl.ClarkLDF(growth="weibull").fit(tri)
+        print(float(np.round(m_log.ldf_.values[0, 0, 0, 0], 3)))
+        print(float(np.round(m_wei.ldf_.values[0, 0, 0, 0], 3)))
+
+    .. testoutput::
+
+        1.917
+        1.912
+
+    Passing ``sample_weight`` switches to Cape Cod: ``method_`` becomes
+    ``cape_cod`` and ``elr_`` is estimated.
+
+    .. testcode::
+
+        tri = cl.load_sample("ukmotor")
+        m = cl.ClarkLDF().fit(tri, sample_weight=tri * 0 + 1e7)
+        print(m.method_)
+        print(float(np.round(m.elr_.values[0, 0], 6)))
+
+    .. testoutput::
+
+        cape_cod
+        0.002002
+
+    ``groupby`` pools index levels before fitting so one parameter set is
+    returned per group (here, line of business on ``clrd``).
+
+    .. testcode::
+
+        clrd = cl.load_sample("clrd").groupby("LOB")[["IncurLoss"]].sum()
+        m = cl.ClarkLDF(groupby="LOB").fit(clrd)
+        print(m.theta_.shape)
+
+    .. testoutput::
+
+        (6, 1)
+
     """
 
     def __init__(

From 9fc573e094c3eb115ba34a72aa626be434ae89a1 Mon Sep 17 00:00:00 2001
From: Ethan Kang <ethan.yskang@gmail.com>
Date: Sat, 16 May 2026 15:53:05 -0700
Subject: [PATCH 2/2] docs: frame ClarkLDF examples around user goals

---
 chainladder/development/clark.py | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/chainladder/development/clark.py b/chainladder/development/clark.py
index c2641e82..269e9016 100644
--- a/chainladder/development/clark.py
+++ b/chainladder/development/clark.py
@@ -56,8 +56,9 @@ class ClarkLDF(DevelopmentBase):
 
     Examples
     --------
-    ``growth`` selects the incremental curve; the first LDF cell moves slightly
-    between ``loglogistic`` (default) and ``weibull``.
+    Compare curve families when the selected growth curve materially affects
+    the fitted development pattern. The same triangle can be fit with the
+    default loglogistic curve or with the Weibull curve.
 
     .. testsetup::
 
@@ -78,8 +79,9 @@ class ClarkLDF(DevelopmentBase):
         1.917
         1.912
 
-    Passing ``sample_weight`` switches to Cape Cod: ``method_`` becomes
-    ``cape_cod`` and ``elr_`` is estimated.
+    Provide exposure when the goal is a Cape Cod fit rather than a pure LDF
+    fit. Passing ``sample_weight`` changes ``method_`` to ``cape_cod`` and
+    estimates ``elr_``.
 
     .. testcode::
 
@@ -93,8 +95,9 @@ class ClarkLDF(DevelopmentBase):
         cape_cod
         0.002002
 
-    ``groupby`` pools index levels before fitting so one parameter set is
-    returned per group (here, line of business on ``clrd``).
+    Pool similar segments before fitting when each individual triangle is too
+    sparse for separate curve parameters. Here line of business produces one
+    parameter set per ``LOB``.
 
     .. testcode::