Move all stochastic randomness to data package for deterministic country package

Remove all random() calls and seed variables from the country package.
Takeup variables (ACA, SNAP, Medicaid) are now formula-less with default True.
WIC uses draw variables instead of random(). SSI resource test uses only
policy logic. Add state-specific Medicaid rates, Section 1931 deprivation
rules, Head Start/Early Head Start takeup variables.

Supersedes #6635, #7317. Fixes #7316.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: baogorek

changelog_entry.yaml

@@ -0,0 +1,17 @@
+- bump: minor
+  changes:
+    added:
+      - State-specific Medicaid takeup rates (53%-99% range, calibrated vs uniform 93%)
+      - Section 1931 deprivation requirement parameter for non-expansion states
+      - is_single_parent_household variable for Medicaid deprivation rules
+      - Head Start and Early Head Start takeup variables
+      - WIC takeup and nutritional risk draw variables (for deterministic microsim)
+      - SSI resource test now uses actual policy logic in individual sim
+    changed:
+      - Moved all stochastic randomness to data package for deterministic country package
+      - is_parent_for_medicaid_nfc now checks Section 1931 deprivation requirements
+      - Head Start and Early Head Start benefits now multiply by takeup
+      - WIC would_claim_wic and is_wic_at_nutritional_risk use draw variables instead of random()
+    removed:
+      - aca_take_up_seed, snap_take_up_seed, medicaid_take_up_seed variables
+      - random() calls from all variable formulas

policyengine_us/parameters/gov/hhs/medicaid/eligibility/categories/parent/requires_deprivation.yaml

@@ -0,0 +1,122 @@
+description: >
+  Whether the state requires a child to be "deprived of parental support"
+  for parent Medicaid eligibility. This is based on Section 1931 criteria
+  which applies to non-expansion states using pre-ACA AFDC rules.
+  In practice, this means two-parent households generally do not qualify
+  unless one parent is incapacitated or unemployed.
+metadata:
+  label: Medicaid parent eligibility requires deprivation
+  unit: bool
+  period: year
+  breakdown:
+    - state_code
+  reference:
+    - title: Section 1931 Medicaid Eligibility
+      href: https://www.law.cornell.edu/uscode/text/42/1396u-1
+    - title: KFF - Medicaid Eligibility for Parents
+      href: https://www.kff.org/medicaid/state-indicator/medicaid-income-eligibility-limits-for-parents/
+# Non-expansion states that use Section 1931 deprivation rules
+AL:
+  2018-01-01: true
+FL:
+  2018-01-01: true
+GA:
+  2018-01-01: true
+KS:
+  2018-01-01: true
+MS:
+  2018-01-01: true
+NC:
+  2018-01-01: true
+  2023-12-01: false  # NC expanded Medicaid
+SC:
+  2018-01-01: true
+SD:
+  2018-01-01: true
+TN:
+  2018-01-01: true
+TX:
+  2018-01-01: true
+WI:
+  2018-01-01: true
+WY:
+  2018-01-01: true
+# Expansion states - no deprivation requirement
+AK:
+  2018-01-01: false
+AR:
+  2018-01-01: false
+AZ:
+  2018-01-01: false
+CA:
+  2018-01-01: false
+CO:
+  2018-01-01: false
+CT:
+  2018-01-01: false
+DC:
+  2018-01-01: false
+DE:
+  2018-01-01: false
+HI:
+  2018-01-01: false
+IA:
+  2018-01-01: false
+ID:
+  2018-01-01: false
+IL:
+  2018-01-01: false
+IN:
+  2018-01-01: false
+KY:
+  2018-01-01: false
+LA:
+  2018-01-01: false
+MA:
+  2018-01-01: false
+MD:
+  2018-01-01: false
+ME:
+  2018-01-01: false
+MI:
+  2018-01-01: false
+MN:
+  2018-01-01: false
+MO:
+  2018-01-01: false
+MT:
+  2018-01-01: false
+ND:
+  2018-01-01: false
+NE:
+  2018-01-01: false
+NH:
+  2018-01-01: false
+NJ:
+  2018-01-01: false
+NM:
+  2018-01-01: false
+NV:
+  2018-01-01: false
+NY:
+  2018-01-01: false
+OH:
+  2018-01-01: false
+OK:
+  2018-01-01: false
+OR:
+  2018-01-01: false
+PA:
+  2018-01-01: false
+RI:
+  2018-01-01: false
+UT:
+  2018-01-01: false
+VA:
+  2018-01-01: false
+VT:
+  2018-01-01: false
+WA:
+  2018-01-01: false
+WV:
+  2018-01-01: false

policyengine_us/parameters/gov/hhs/medicaid/takeup_rate.yaml

@@ -1,12 +1,116 @@
 description: Percentage of people who do enroll in Medicaid, if eligible.
-values:
-  2018-01-01: 0.93
 metadata:
   label: Medicaid takeup rate
   unit: /1
   period: year
   economy: false
   household: false
+  breakdown:
+    - state_code
   reference:
     - title: KFF "A Closer Look at the Remaining Uninsured Population Eligible for Medicaid and CHIP"
-      href: https://www.kff.org/uninsured/issue-brief/a-closer-look-at-the-remaining-uninsured-population-eligible-for-medicaid-and-chip/#:~:text=the%20uninsured%20rate%20dropped%20to,States%20began%20the
+      href: https://www.kff.org/uninsured/issue-brief/a-closer-look-at-the-remaining-uninsured-population-eligible-for-medicaid-and-chip/
+    - title: State-specific rates derived from MACPAC enrollment targets vs modeled eligibility
+      href: https://www.medicaid.gov/medicaid/program-information/medicaid-and-chip-enrollment-data/report-highlights/index.html
+AK:
+  2018-01-01: 0.88
+AL:
+  2018-01-01: 0.92
+AR:
+  2018-01-01: 0.79
+AZ:
+  2018-01-01: 0.95
+CA:
+  2018-01-01: 0.78
+CO:
+  2018-01-01: 0.99
+CT:
+  2018-01-01: 0.89
+DC:
+  2018-01-01: 0.99
+DE:
+  2018-01-01: 0.86
+FL:
+  2018-01-01: 0.98
+GA:
+  2018-01-01: 0.73
+HI:
+  2018-01-01: 0.88
+IA:
+  2018-01-01: 0.84
+ID:
+  2018-01-01: 0.78
+IL:
+  2018-01-01: 0.85
+IN:
+  2018-01-01: 0.99
+KS:
+  2018-01-01: 0.92
+KY:
+  2018-01-01: 0.87
+LA:
+  2018-01-01: 0.79
+MA:
+  2018-01-01: 0.94
+MD:
+  2018-01-01: 0.95
+ME:
+  2018-01-01: 0.92
+MI:
+  2018-01-01: 0.91
+MN:
+  2018-01-01: 0.89
+MO:
+  2018-01-01: 0.89
+MS:
+  2018-01-01: 0.75
+MT:
+  2018-01-01: 0.83
+NC:
+  2018-01-01: 0.94
+ND:
+  2018-01-01: 0.91
+NE:
+  2018-01-01: 0.79
+NH:
+  2018-01-01: 0.84
+NJ:
+  2018-01-01: 0.74
+NM:
+  2018-01-01: 0.84
+NV:
+  2018-01-01: 0.93
+NY:
+  2018-01-01: 0.86
+OH:
+  2018-01-01: 0.82
+OK:
+  2018-01-01: 0.77
+OR:
+  2018-01-01: 0.92
+PA:
+  2018-01-01: 0.64
+RI:
+  2018-01-01: 0.94
+SC:
+  2018-01-01: 0.93
+SD:
+  2018-01-01: 0.88
+TN:
+  2018-01-01: 0.92
+TX:
+  2018-01-01: 0.76
+UT:
+  2018-01-01: 0.53
+VA:
+  2018-01-01: 0.82
+VT:
+  2018-01-01: 0.93
+WA:
+  2018-01-01: 0.98
+WI:
+  2018-01-01: 0.91
+WV:
+  2018-01-01: 0.83
+WY:
+  2018-01-01: 0.70

policyengine_us/tests/policy/baseline/gov/aca/ptc/takes_up_aca_if_eligible.yaml

@@ -1,29 +1,28 @@
 # Nutritional risk is a health assessment per 42 U.S.C. § 1786(b)(8).
-# In individual simulation, all persons are assumed at nutritional risk.
+# In individual simulation, draw defaults to 0, so all persons in a
+# WIC-eligible category are assessed at nutritional risk (0 < rate).
 # In microsimulation, risk is assigned probabilistically by category.
 
-- name: Case 1, infant assumed at nutritional risk in individual simulation.
+- name: Case 1, infant at nutritional risk (draw=0, INFANT rate=0.95).
   period: 2024-01
   input:
     age: 0
   output:
     is_wic_at_nutritional_risk: true
 
-- name: Case 2, child assumed at nutritional risk in individual simulation.
+- name: Case 2, child at nutritional risk (draw=0, CHILD rate=0.752).
   period: 2024-01
   input:
     age: 3
   output:
     is_wic_at_nutritional_risk: true
 
-- name: Case 3, adult assumed at nutritional risk in individual simulation.
+- name: Case 3, non-WIC adult not at nutritional risk (NONE rate=0).
   period: 2024-01
   input:
     age: 35
   output:
-    # Even adults are assumed at nutritional risk in individual simulation.
-    # Demographic eligibility is checked separately in is_wic_eligible.
-    is_wic_at_nutritional_risk: true
+    is_wic_at_nutritional_risk: false
 
 - name: Case 4, person receiving WIC is at nutritional risk.
   period: 2024-01

policyengine_us/tests/policy/baseline/gov/hhs/medicaid/takes_up_medicaid_if_eligible.yaml

@@ -3,6 +3,7 @@
   input:
     wic_category_str: PREGNANT
     is_wic_eligible: true
+    would_claim_wic: true
   output:
     wic: 37.33
 
@@ -12,29 +13,31 @@
     wic_category_str: INFANT
     is_wic_eligible: false
   output:
-    wic: 0 
+    wic: 0
 
 - name: Households that are in postpartum category are eligible.
   period: 2018-01
   input:
     wic_category_str: POSTPARTUM
     is_wic_eligible: true
+    would_claim_wic: true
   output:
-    wic: 30.72 
+    wic: 30.72
 
 - name: Meets eligible test but not one of the WIC demographic categories.
   period: 2022-01
   input:
     wic_category_str: NONE
     is_wic_eligible: true
   output:
-    wic: 0 
+    wic: 0
 
 - name: Eligible breastfeeding individuals. Verifies uprating.
   period: 2022-01
   input:
     wic_category_str: BREASTFEEDING
     is_wic_eligible: true
+    would_claim_wic: true
   output:
     # Multiply by ratio of 2022-01 to 2018-01 CPI-U.
     wic: 37.76 * 281.148 / 247.867