[tomjemmett]

closes #703, closes #704, closes #705

updates the model and the parameters schema to remove support for multiple variants to be used within a model run, and to pass the demographic/birth factors directly in the params file, rather than reading these values from disk

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You can use the following to use pull the image into your local environment:

docker pull ghcr.io/the-strategy-unit/nhp_model:pr-701

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (a52ce6b) to head (00851fe).

Additional details and impacted files

@@                    Coverage Diff                    @@
##           remove_tretspef_grouped      #701   +/-   ##
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  Coverage                   100.00%   100.00%           
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  Files                           20        20           
  Lines                         1214      1196   -18     
  Branches                        61        61           
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- Hits                          1214      1196   -18     

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[Copilot]

🟡 Changes recommended

Removing the "variant" key from generate_run_params leaves run_all (run.py:172) reading run_params["variant"], which will raise a runtime KeyError that the mocked unit tests do not catch.

2 open issues

• run_all still reads removed variant key from run_params · New
• Update _load_demog_factors docstring for new demographic state · New

What changed in this PR

This PR implements the demographic-adjustment rework described in issues #703–#705. It removes the model's support for selecting among multiple population variants per model run and stops reading demographic/birth factors from parquet files on disk. Instead, the demographic and birth growth factors are now supplied directly in the parameters file under a new demographic_adjustment object, and _load_demog_factors computes the growth factors (horizon ÷ baseline) into pd.Series keyed by (sex, age). This supports custom population projections without changing the data pipeline.

Changes:

• generate_run_params no longer selects variants/probabilities, and _load_demog_factors builds demog_factors/birth_factors Series from params["demographic_adjustment"] rather than from the data loader.
• The Data/Local interfaces drop get_demographic_factors/get_birth_factors, and activity_resampling consumes the new (sex, age)-indexed Series directly.
• The params schema and sample are restructured to embed demographic_adjustment (variant + population/births baseline/horizon tables), with tests and golden-file snapshots updated accordingly.

File	Description
src/​nhp/​model/​model.py	Rewrites _load_demog_factors to build Series from params and removes variant selection from generate_run_params; docstring left stale.
src/​nhp/​model/​activity_resampling.py	Simplifies demographic/birth adjustments to use the new (sex, age) Series directly.
src/​nhp/​model/​data/​local.py	Removes get_demographic_factors/get_birth_factors loaders.
src/​nhp/​model/​data/​data.py	Removes the abstract get_demographic_factors/get_birth_factors interface methods.
src/​nhp/​model/​params/​params-schema.json	Replaces demographic_factors.variant_probabilities with the demographic_adjustment object and supporting $defs.
src/​nhp/​model/​params/​params-sample.json	Embeds the full population/births baseline/horizon tables.
tests/​unit/​nhp/​model/​test_model.py	Updates demog-factor and run-param tests to the new Series/params shape.
tests/​unit/​nhp/​model/​test_activity_resampling.py	Updates fixtures/assertions to the (demog_type, sex, age) index.
tests/​unit/​nhp/​model/​data/​test_local.py	Removes tests for deleted loader methods.
tests/​unit/​nhp/​model/​data/​test_data.py	Removes tests for deleted abstract methods.
tests/​integration/​.../​*.csv, tests/​e2e/​.../​*.csv	Regenerated golden snapshots reflecting the new computation.

_{Review effort: Balanced}