Use baseline theta

[jdebacker]

This PR updates OG-Core with a new parameter, baseline_theta. If baseline_theta=True, then the reform run uses the same replacement rate in the Social Security pension system as was computed in the baseline simulation.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.87097% with 41 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.92%. Comparing base (cb0e9df) to head (f9e34c1).
⚠️ Report is 131 commits behind head on master.

Files with missing lines	Patch %	Lines
ogcore/SS.py	27.02%	27 Missing ⚠️
ogcore/TPI.py	0.00%	14 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1077      +/-   ##
==========================================
- Coverage   72.92%   72.92%   -0.01%     
==========================================
  Files          21       21              
  Lines        5090     5122      +32     
==========================================
+ Hits         3712     3735      +23     
- Misses       1378     1387       +9     

Flag	Coverage Δ
unittests	72.92% <33.87%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
ogcore/__init__.py	100.00% <100.00%> (ø)
ogcore/pensions.py	68.34% <100.00%> (+0.46%)	⬆️
ogcore/TPI.py	33.48% <0.00%> (-0.94%)	⬇️
ogcore/SS.py	81.01% <27.02%> (+1.38%)	⬆️

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[rickecon]

@jdebacker. I have reviewed and approved this PR. I will merge it as soon as all the tests pass.

[rickecon]

@jdebacker. This breaks when doing the reform simulation. I got the following traceback after a run finished the baseline TPI solution and moved to the reform SS solution.

File "/opt/anaconda3/envs/ss-maxben-j-dev/lib/python3.13/site-packages/ogcore/SS.py", line 66, in euler_equation_solver
    error1 = household.FOC_savings(
        r,
    ...<17 lines>...
        "SS",
    )
  File "/opt/anaconda3/envs/ss-maxben-j-dev/lib/python3.13/site-packages/ogcore/household.py", line 494, in FOC_savings
    taxes = tax.net_taxes(
        r,
    ...<14 lines>...
        p,
    )
  File "/opt/anaconda3/envs/ss-maxben-j-dev/lib/python3.13/site-packages/ogcore/tax.py", line 285, in net_taxes
    pension = pensions.pension_amount(
        r, w, n, 1, theta, t, j, shift, method, e, factor, p
    )
  File "/opt/anaconda3/envs/ss-maxben-j-dev/lib/python3.13/site-packages/ogcore/pensions.py", line 98, in pension_amount
    pension = SS_amount(w, n, theta, t, j, shift, method, e, p)
  File "/opt/anaconda3/envs/ss-maxben-j-dev/lib/python3.13/site-packages/ogcore/pensions.py", line 159, in SS_amount
    pension[p.retire[-1] :] = replace_rate_adjust * theta * w
    ~~~~~~~^^^^^^^^^^^^^^^^
ValueError: could not broadcast input array from shape (7,) into shape (36,)

[jdebacker]

@rickecon Good catch on the error above. I fixed the case for baseline_theta=True and j not None in pensions.replacement_rate_vals. I also added a test to cover this case.

[jdebacker]

All tests pass locally:

tests/test_SS.py ...........................                             [  4%]
tests/test_TPI.py ...........................                                                       [  9%]
tests/test_aggregates.py .........................................                                  [ 16%]
tests/test_basic.py ....                                                                            [ 16%]
tests/test_demographics.py ................                                                         [ 20%]
tests/test_elliptical_u_est.py .......                                                              [ 21%]
tests/test_execute.py .                                                                             [ 21%]
tests/test_firm.py .....................................................................                                                                                    [ 33%]
tests/test_fiscal.py ......................                                                         [ 37%]
tests/test_household.py ..................................................                                                                                                  [ 45%]
tests/test_output_plots.py ...............................................                                                                                                  [ 53%]
tests/test_output_tables.py ..............                                                          [ 56%]
tests/test_parameter_plots.py ........................................                              [ 62%]
tests/test_parameter_tables.py .......                                                              [ 64%]
tests/test_parameters.py ..............                                                             [ 66%]
tests/test_pensions.py .................................                                            [ 71%]
tests/test_run_example.py ..                                                                        [100%]
tests/test_run_ogcore.py .                                                                          [100%]
tests/test_tax.py ...................................                                               [100%]
tests/test_txfunc.py ..............................                                                 [100%]
tests/test_user_inputs.py .........                                                                 [100%]
tests/test_utils.py ...................................................................................                                                                                       [100%]

[rickecon]

@jdebacker. I pulled this branch, updated the conda environment, and ran the run_ogcore_example.py script. Script ran smoothly through all phases of baseline and reform, steady state and time path. I am merging this.