Round 11: summary() footer branches on inference mode

P2 fix: summary() was unconditionally printing "dCDH analytical CI
is conservative under Assumption 8" even when n_bootstrap > 0 and
the displayed p_value / conf_int were bootstrap-based. The footer
now branches on bootstrap_results: when bootstrap is active, it
prints "p-value and CI are multiplier-bootstrap percentile inference
(N iterations, weight_type weights)"; when analytical, it keeps the
original conservative-CI note.

Added test assertions pinning both paths:
- test_summary_formats_without_error (analytical mode): asserts
  "analytical CI is conservative" is present and "multiplier-
  bootstrap" is absent
- test_bootstrap_p_value_and_ci_propagated_to_top_level (bootstrap
  mode): asserts "multiplier-bootstrap percentile inference" is
  present and "analytical CI is conservative" is absent

111 tests still pass; black, ruff clean.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: igerber

diff_diff/chaisemartin_dhaultfoeuille_results.py

@@ -520,10 +520,18 @@ def summary(self, alpha: Optional[float] = None) -> str:
             lines.append(f"{'CV (SE/|DID_M|):':<25} {cv:>10.4f}")
 
         lines.append("")
-        lines.append(
-            "Note: dCDH analytical CI is conservative under Assumption 8" " (independent groups);"
-        )
-        lines.append("      exact under iid sampling.")
+        if self.bootstrap_results is not None:
+            lines.append("Note: p-value and CI are multiplier-bootstrap percentile inference")
+            lines.append(
+                f"      ({self.bootstrap_results.n_bootstrap} iterations, "
+                f"{self.bootstrap_results.weight_type} weights)."
+            )
+        else:
+            lines.append(
+                "Note: dCDH analytical CI is conservative under Assumption 8"
+                " (independent groups);"
+            )
+            lines.append("      exact under iid sampling.")
         lines.append("")
 
         # --- Joiners and leavers ---

tests/test_chaisemartin_dhaultfoeuille.py

@@ -1043,6 +1043,11 @@ def test_bootstrap_p_value_and_ci_propagated_to_top_level(self, data, ci_params)
         # the bootstrap output.
         summary_text = results.summary()
         assert "DID_M" in summary_text
+        # The summary footer should mention bootstrap inference, NOT
+        # the analytical-CI conservativeness note (which only applies
+        # when n_bootstrap=0). This pins the P2 fix from Round 11.
+        assert "multiplier-bootstrap percentile inference" in summary_text
+        assert "analytical CI is conservative" not in summary_text
         df_overall = results.to_dataframe(level="overall")
         assert df_overall.iloc[0]["p_value"] == pytest.approx(br.overall_p_value)
         assert df_overall.iloc[0]["conf_int_lower"] == pytest.approx(br.overall_ci[0])
@@ -1090,6 +1095,9 @@ def test_summary_formats_without_error(self, results):
         assert "DID_M" in out
         assert "DID_+" in out
         assert "DID_-" in out
+        # Analytical mode (n_bootstrap=0) shows the conservative-CI note
+        assert "analytical CI is conservative" in out
+        assert "multiplier-bootstrap" not in out
 
     def test_print_summary(self, results, capsys):
         results.print_summary()