Child limit targets need 2024-25 uprating

Fixes #116

Author: nikhilwoodruff

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    fixed:
+    - Uprating in child limit target.

policyengine_uk_data/tests/test_child_limit.py

@@ -29,8 +29,13 @@ def test_child_limit():
     ).sum()
     households_affected = (capped_households * household_weight).sum()
 
-    child_target = 1.6e6  # Expected number of affected children
-    household_target = 440e3  # Expected number of affected households
+    UPRATING_24_25 = 1.12  # https://ifs.org.uk/articles/two-child-limit-poverty-incentives-and-cost, table at the end
+    child_target = (
+        1.6e6 * UPRATING_24_25
+    )  # Expected number of affected children
+    household_target = (
+        440e3 * UPRATING_24_25
+    )  # Expected number of affected households
 
     assert (
         abs(children_affected / child_target - 1) < 0.1

policyengine_uk_data/utils/loss.py

@@ -252,11 +252,12 @@ def pe_count(*variables):
         children_in_capped_households
     )
     target_names.append("dwp/uc_two_child_limit_affected_child_count")
-    target_values.append(1.6e6)  # DWP statistics for 2024/25
+    UPRATING_24_25 = 1.12  # https://ifs.org.uk/articles/two-child-limit-poverty-incentives-and-cost, table at the end
+    target_values.append(1.6e6 * UPRATING_24_25)  # DWP statistics for 2024/25
     # https://www.gov.uk/government/statistics/universal-credit-and-child-tax-credit-claimants-statistics-related-to-the-policy-to-provide-support-for-a-maximum-of-2-children-april-2024/universal-credit-and-child-tax-credit-claimants-statistics-related-to-the-policy-to-provide-support-for-a-maximum-of-two-children-april-2024
     df["dwp/uc_two_child_limit_affected_household_count"] = capped_households
     target_names.append("dwp/uc_two_child_limit_affected_household_count")
-    target_values.append(440e3)  # DWP statistics for 2024/25
+    target_values.append(440e3 * UPRATING_24_25)  # DWP statistics for 2024/25
 
     combined_targets = pd.concat(
         [