Repository navigation
Re-measure UC composition errors after first calibrated run; element references still unsourced #738
Description
The UK contract carries 30 UC target ids; the national calibration activates 1 of them. 29 are declared, mapped and inert.
uk/uk_national_targets.json — 30 dwp.uc.* ids of 187 total, split evenly:
dwp_universal_credit 15 (households, 4 family types, 5 child counts, payment bands, Scotland)
dwp_two_child_limit 15
uk/target_references.json — 15 references, of which UC is:
dwp.uc.households period=2025 entity=benunit measure=dwp/uc/households
obr.universal_credit_in_cap period=2025 entity=benunit measure=obr/universal_credit_in_cap
So national_calibration.py calibrates UC on one caseload count and one expenditure aggregate. The family-type and child-count composition is unconstrained, and this is where the error actually sits (policyengine-uk-data, enhanced FRS 2023-24 v1.56.16, 2025):
| Target | Model | DWP | Err |
|---|---|---|---|
dwp.uc.households (activated) |
6.395m | 6.700m | -4.6% |
households_single_no_children |
3.210m | 2.868m | +11.9% |
households_couple_no_children |
0.280m | 0.231m | +21.1% |
households_children_3 |
0.369m | 0.473m | -22.0% |
households_children_4 |
0.136m | 0.167m | -18.3% |
households_children_5_or_more |
0.064m | 0.076m | -16.2% |
The one activated count is the best-fitting number in the set. Activating the composition rows is what moves the double-digit errors.
Blocker on the two-child limit half: all 15 dwp_two_child_limit ids resolve to targets that are structurally zero from 2026-04-06 (limit abolished, Budget 2025). See PolicyEngine/policyengine-uk-data#465 — activating them before that lands would calibrate against zero.
Not a defect, checked: the payment-distribution many-to-one mapping is correct — dwp.uc.payment_distribution_* carries groupby_dimension: dwp.uc_monthly_award_band, so the per-band uk-data names collapse to one banded id by design.
Next steps
- Activate the 4 family-type and 5 child-count references at period 2025, alongside the existing
dwp.uc.households. Needs the chronicle facts for those ids. - Keep the 15 two-child-limit ids deferred until uk-data#465 moves them to 2025.
- Element-level references (housing, LCWRA, carer, childcare) have no contract ids at all yet — they land here only after uk-data#466 adds the targets upstream.
Activity
juaristi22 commentedon Aug 21, 2026
Mapped against #735 (now rebased onto main with the post-chronicle#184 feed): the activation gap this issue measures is closed by that PR — the 15-reference file analyzed here was the #729-era surface, which #735's regeneration replaces with 388 active references.
Per next-step:
households_{single,couple}_{no,with}_children,households_children_1..5_or_more) plus Scotland under-1 — the chronicle facts existed (DWP monthlies at 2025-05); only the pre-Complete #622: compile the UK target surface from Ledger facts at the 2024-25 line #735 references file predated them.dwp.uc.householdsitself now compiles with the adjudicatedcalendar_year_averageover the Add proximal L1 solver path #184 caseload series: 6,758,889 vs DWP's 6,700,000 (+0.9%, signed). The payment bands are 100 active fan-out references (matching the many-to-one check above).UC_Households), then a contract amendment per the Refresh the UK Universal Credit target contract #727 precedent, then references activate automatically. Registered as microcosm#736 item 12, alongside the monthly split history that makes the family-type values sum-consistent with the caseload average (this issue's vintage-tension note).What activation alone does NOT fix: the model-vs-DWP error table above comes from a calibrated release — those numbers move only when a calibration run binds the new surface (the #729 stage consumes all 388 references; run-readiness is the narrowed #623). Suggest keeping this issue open to re-measure the composition errors after the first calibrated candidate, with the remaining scope being that re-measurement plus item 3.
vahid-ahmadi commentedon Aug 24, 2026
Verified against main and agreed — items 1 and 2 are closed by #735. Confirming what I checked:
You are right on point 2 and I was wrong to call uk-data#465 a blocker here: binding the April-2025 facts at 2025 sidesteps the abolition entirely, so nothing on this side is gated on it. #465 is a standalone defect in the uk-data registry (
sources/dwp.py:209-303, still{2026}on main) and I have corrected my cross-link there.One clarification for anyone reading the table in the issue body: your 6,758,889 vs 6,700,000 (+0.9%) is the compiled target value; the -4.6% in the table is the model estimate against that target. Both are right, they measure different things, and only the second is what a calibration run moves.
Agreed on keeping this open to re-measure after the first calibrated candidate. Narrowing scope to:
Remaining
cc @MaxGhenis @vahid-ahmadi
[-]UK national calibration activates 1 of 30 UC contract targets; family-type composition unconstrained[/-][+]Re-measure UC composition errors after first calibrated run; element references still unsourced[/+]juaristi22 commentedon Sep 9, 2026
Closing as superseded by #882. Composition activation and the first candidate remeasurement are complete. The scope-transfer note carries forward remeasurement after the remaining repairs and the outstanding comparable UC element bindings, including the limits of the available Chronicle series.