Add ONS land value calibration targets

changelog.d/add-ons-land-value-targets.added.md

@@ -0,0 +1 @@
+Add ONS land value calibration targets (household, corporate, total land, property wealth) from the National Balance Sheet 2025.

policyengine_uk_data/targets/build_loss_matrix.py

@@ -30,6 +30,7 @@
     compute_household_type,
     compute_housing,
     compute_income_band,
+    compute_land_value,
     compute_obr_council_tax,
     compute_pip_claimants,
     compute_regional_age,
@@ -289,6 +290,15 @@ def _compute_column(target: Target, ctx: _SimContext, year: int) -> np.ndarray |
     if name in ("housing/total_mortgage", "housing/rent_private"):
         return compute_housing(target, ctx)
 
+    # Land and property wealth (ONS National Balance Sheet)
+    if name in (
+        "ons/household_land_value",
+        "ons/corporate_land_value",
+        "ons/land_value",
+        "ons/property_wealth",
+    ):
+        return compute_land_value(target, ctx)
+
     # Savings
     if name == "ons/savings_interest_income":
         return compute_savings_interest(target, ctx)

policyengine_uk_data/targets/compute/__init__.py

@@ -35,6 +35,7 @@
 )
 from policyengine_uk_data.targets.compute.other import (
     compute_housing,
+    compute_land_value,
     compute_savings_interest,
     compute_scottish_child_payment,
     compute_student_loan_plan,
@@ -48,6 +49,7 @@
     "compute_gender_age",
     "compute_household_type",
     "compute_housing",
+    "compute_land_value",
     "compute_income_band",
     "compute_obr_council_tax",
     "compute_pip_claimants",

policyengine_uk_data/targets/compute/other.py

@@ -49,6 +49,11 @@ def compute_scottish_child_payment(target, ctx) -> np.ndarray:
     return ctx.household_from_person(scp)
 
 
+def compute_land_value(target, ctx) -> np.ndarray:
+    """Compute land/property wealth targets from household-level variables."""
+    return ctx.pe(target.variable)
+
+
 def compute_student_loan_plan(target, ctx) -> np.ndarray:
     """Count England borrowers on a given plan with repayments > 0.
 

policyengine_uk_data/targets/sources/ons_land_values.py

@@ -0,0 +1,83 @@
+"""ONS National Balance Sheet land value targets.
+
+Aggregate land values from the ONS National Balance Sheet 2025.
+The ONS directly measured total UK land at £7.1 trillion for 2024,
+broken down into household land (£4.31tn in 2020) and corporate
+land (£1.76tn in 2020).
+
+Source: https://www.ons.gov.uk/economy/nationalaccounts/uksectoraccounts/bulletins/nationalbalancesheet/2025
+"""
+
+from policyengine_uk_data.targets.schema import Target, Unit
+
+# ONS National Balance Sheet 2025
+# 2020 breakdown: household £4.31tn, corporate £1.76tn, total £6.07tn
+# 2024 measured total: £7.1tn
+# We scale the 2020 household/corporate split proportionally to match
+# the 2024 measured total, then hold constant for 2025-2026 (no newer
+# ONS measurement available).
+
+_ONS_2020_HOUSEHOLD = 4.31e12
+_ONS_2020_CORPORATE = 1.76e12
+_ONS_2020_TOTAL = _ONS_2020_HOUSEHOLD + _ONS_2020_CORPORATE
+_ONS_2024_TOTAL = 7.1e12
+
+# Scale 2020 split to 2024 measured total
+_SCALE = _ONS_2024_TOTAL / _ONS_2020_TOTAL
+_ONS_2024_HOUSEHOLD = _ONS_2020_HOUSEHOLD * _SCALE
+_ONS_2024_CORPORATE = _ONS_2020_CORPORATE * _SCALE
+
+_REF_URL = "https://www.ons.gov.uk/economy/nationalaccounts/uksectoraccounts/bulletins/nationalbalancesheet/2025"
+
+
+def get_targets() -> list[Target]:
+    return [
+        Target(
+            name="ons/household_land_value",
+            variable="household_land_value",
+            source="ons",
+            unit=Unit.GBP,
+            values={
+                2024: _ONS_2024_HOUSEHOLD,
+                2025: _ONS_2024_HOUSEHOLD,
+                2026: _ONS_2024_HOUSEHOLD,
+            },
+            reference_url=_REF_URL,
+        ),
+        Target(
+            name="ons/corporate_land_value",
+            variable="corporate_land_value",
+            source="ons",
+            unit=Unit.GBP,
+            values={
+                2024: _ONS_2024_CORPORATE,
+                2025: _ONS_2024_CORPORATE,
+                2026: _ONS_2024_CORPORATE,
+            },
+            reference_url=_REF_URL,
+        ),
+        Target(
+            name="ons/land_value",
+            variable="land_value",
+            source="ons",
+            unit=Unit.GBP,
+            values={
+                2024: _ONS_2024_TOTAL,
+                2025: _ONS_2024_TOTAL,
+                2026: _ONS_2024_TOTAL,
+            },
+            reference_url=_REF_URL,
+        ),
+        Target(
+            name="ons/property_wealth",
+            variable="property_wealth",
+            source="ons",
+            unit=Unit.GBP,
+            values={
+                2024: _ONS_2024_TOTAL,
+                2025: _ONS_2024_TOTAL,
+                2026: _ONS_2024_TOTAL,
+            },
+            reference_url=_REF_URL,
+        ),
+    ]

policyengine_uk_data/tests/test_land_value_targets.py

@@ -0,0 +1,88 @@
+"""Tests for ONS land value calibration targets.
+
+These validate that the generated Enhanced FRS dataset reproduces
+aggregate land and property wealth values from the ONS National
+Balance Sheet 2025.
+
+Source: https://www.ons.gov.uk/economy/nationalaccounts/uksectoraccounts/bulletins/nationalbalancesheet/2025
+"""
+
+import pytest
+
+# ONS National Balance Sheet 2025
+# 2024 measured total: £7.1tn
+# 2020 split scaled proportionally: household £5.04tn, corporate £2.06tn
+_ONS_2020_HOUSEHOLD = 4.31e12
+_ONS_2020_CORPORATE = 1.76e12
+_ONS_2020_TOTAL = _ONS_2020_HOUSEHOLD + _ONS_2020_CORPORATE
+_ONS_2024_TOTAL = 7.1e12
+_SCALE = _ONS_2024_TOTAL / _ONS_2020_TOTAL
+
+LAND_TARGETS = {
+    "land_value": _ONS_2024_TOTAL,
+    "household_land_value": _ONS_2020_HOUSEHOLD * _SCALE,
+    "corporate_land_value": _ONS_2020_CORPORATE * _SCALE,
+    "property_wealth": _ONS_2024_TOTAL,
+}
+
+YEAR = 2025
+TOLERANCE = 0.30  # 30% relative error allowed
+
+
+@pytest.mark.xfail(reason="Will pass after recalibration with ONS land value targets")
+@pytest.mark.parametrize(
+    "variable,target",
+    list(LAND_TARGETS.items()),
+    ids=list(LAND_TARGETS.keys()),
+)
+def test_land_value_aggregate(baseline, variable, target):
+    """Check weighted aggregate land/property values against ONS targets."""
+    weights = baseline.calculate("household_weight", period=YEAR).values
+    values = baseline.calculate(variable, map_to="household", period=YEAR).values
+    estimate = (values * weights).sum()
+
+    rel_error = abs(estimate / target - 1)
+    assert rel_error < TOLERANCE, (
+        f"{variable}: expected £{target / 1e12:.2f}tn, "
+        f"got £{estimate / 1e12:.2f}tn "
+        f"(relative error = {rel_error:.1%})"
+    )
+
+
+@pytest.mark.xfail(reason="Will pass after recalibration with ONS land value targets")
+def test_land_value_composition(baseline):
+    """Household + corporate land should equal total land value."""
+    weights = baseline.calculate("household_weight", period=YEAR).values
+    total = baseline.calculate("land_value", map_to="household", period=YEAR).values
+    hh = baseline.calculate(
+        "household_land_value", map_to="household", period=YEAR
+    ).values
+    corp = baseline.calculate(
+        "corporate_land_value", map_to="household", period=YEAR
+    ).values
+
+    total_agg = (total * weights).sum()
+    sum_agg = ((hh + corp) * weights).sum()
+
+    assert abs(total_agg / sum_agg - 1) < 0.01, (
+        f"Total land (£{total_agg / 1e12:.2f}tn) should equal "
+        f"household + corporate (£{sum_agg / 1e12:.2f}tn)"
+    )
+
+
+@pytest.mark.xfail(reason="Will pass after recalibration with ONS land value targets")
+def test_household_land_less_than_property_wealth(baseline):
+    """Household land value should not exceed total property wealth."""
+    weights = baseline.calculate("household_weight", period=YEAR).values
+    hh_land = baseline.calculate(
+        "household_land_value", map_to="household", period=YEAR
+    ).values
+    prop = baseline.calculate("property_wealth", map_to="household", period=YEAR).values
+
+    hh_land_agg = (hh_land * weights).sum()
+    prop_agg = (prop * weights).sum()
+
+    assert hh_land_agg <= prop_agg * 1.05, (
+        f"Household land (£{hh_land_agg / 1e12:.2f}tn) should not "
+        f"exceed property wealth (£{prop_agg / 1e12:.2f}tn)"
+    )