{"abstract":"Pooling a disproportionate stratified sample changes expansion totals.","category":"Survey sampling estimators","checks":6,"contract":"Strata are (known population count, nonempty sampled values); zero-population strata may have empty samples. Return None for an unsampled positive stratum; otherwise rounded total.","evaluation_group":"model-81ffcaf7f4803623","failed_approach":"Using a common expansion factor still ignores disproportionate allocation.","family":"z-survey_sampling-stratum-populations","id":"FA-12601","implementations":{"attempt":{"sha256":"b6a25db79ab832c4d7d5e5febb0d483de9bcd3d95fd89caad40f62b619f70419","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(strata):\n    values=[x for size,v in strata for x in v]\n    return round(sum(size for size,v in strata)*sum(values)/len(values),8) if values else 0\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('disproportionate allocation',solve([(10,[N]),(2,[3*N,3*N])]),16*N)\ncheck('single stratum expansion',solve([(8,[N,3*N])]),16*N)\ncheck('census strata',solve([(1,[N]),(2,[2*N,4*N])]),7*N)\ncheck('empty zero stratum',solve([(0,[]),(4,[N])]),4*N)\ncheck('unobserved positive stratum',solve([(3,[])]),None)\ncheck('empty frame',solve([]),0)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"caf3fc80ae89dd22513992acf50920672056c29da51cc024db5fa235d87218b7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(strata):\n    return sum(sum(v) for size,v in strata)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('disproportionate allocation',solve([(10,[N]),(2,[3*N,3*N])]),16*N)\ncheck('single stratum expansion',solve([(8,[N,3*N])]),16*N)\ncheck('census strata',solve([(1,[N]),(2,[2*N,4*N])]),7*N)\ncheck('empty zero stratum',solve([(0,[]),(4,[N])]),4*N)\ncheck('unobserved positive stratum',solve([(3,[])]),None)\ncheck('empty frame',solve([]),0)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"b5c1085affb9f9eaa94fd1b73084855fa8c5a145f650fdf126d4dfd1b6b4ed17","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(strata):\n    if any(size>0 and not v for size,v in strata): return None\n    return round(sum(size*sum(v)/len(v) for size,v in strata if size),8)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('disproportionate allocation',solve([(10,[N]),(2,[3*N,3*N])]),16*N)\ncheck('single stratum expansion',solve([(8,[N,3*N])]),16*N)\ncheck('census strata',solve([(1,[N]),(2,[2*N,4*N])]),7*N)\ncheck('empty zero stratum',solve([(0,[]),(4,[N])]),4*N)\ncheck('unobserved positive stratum',solve([(3,[])]),None)\ncheck('empty frame',solve([]),0)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Controlled finite fixtures; not a general survey-analysis package. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"z-survey_sampling-stratum-populations","generated_at":"2026-09-29T14:38:58.408963+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic survey-design model isolates this sampling contract before it is embedded in a larger estimation pipeline.","repair":"Expand each stratum mean by its own known population count.","root_cause":"Observed values are pooled without preserving population stratum sizes.","sha256":"71b62470b64308c45fc2e38cbde6cef4e849f47a3759b0f2fed5fb81b2b3556a","title":"Pooling a disproportionate stratified sample changes expansion totals · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":40.862,"exit_code":1,"observations":[{"actual":28.0,"check":"disproportionate allocation","expected":16,"passed":false},{"actual":16.0,"check":"single stratum expansion","expected":16,"passed":true},{"actual":7.0,"check":"census strata","expected":7,"passed":true},{"actual":4.0,"check":"empty zero stratum","expected":4,"passed":true},{"actual":0,"check":"unobserved positive stratum","expected":null,"passed":false},{"actual":0,"check":"empty frame","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"disproportionate allocation\", \"actual\": 28.0, \"expected\": 16, \"passed\": false}, {\"check\": \"single stratum expansion\", \"actual\": 16.0, \"expected\": 16, \"passed\": true}, {\"check\": \"census strata\", \"actual\": 7.0, \"expected\": 7, \"passed\": true}, {\"check\": \"empty zero stratum\", \"actual\": 4.0, \"expected\": 4, \"passed\": true}, {\"check\": \"unobserved positive stratum\", \"actual\": 0, \"expected\": null, \"passed\": false}, {\"check\": \"empty frame\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.238,"exit_code":1,"observations":[{"actual":7,"check":"disproportionate allocation","expected":16,"passed":false},{"actual":4,"check":"single stratum expansion","expected":16,"passed":false},{"actual":7,"check":"census strata","expected":7,"passed":true},{"actual":1,"check":"empty zero stratum","expected":4,"passed":false},{"actual":0,"check":"unobserved positive stratum","expected":null,"passed":false},{"actual":0,"check":"empty frame","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"disproportionate allocation\", \"actual\": 7, \"expected\": 16, \"passed\": false}, {\"check\": \"single stratum expansion\", \"actual\": 4, \"expected\": 16, \"passed\": false}, {\"check\": \"census strata\", \"actual\": 7, \"expected\": 7, \"passed\": true}, {\"check\": \"empty zero stratum\", \"actual\": 1, \"expected\": 4, \"passed\": false}, {\"check\": \"unobserved positive stratum\", \"actual\": 0, \"expected\": null, \"passed\": false}, {\"check\": \"empty frame\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.533,"exit_code":0,"observations":[{"actual":16.0,"check":"disproportionate allocation","expected":16,"passed":true},{"actual":16.0,"check":"single stratum expansion","expected":16,"passed":true},{"actual":7.0,"check":"census strata","expected":7,"passed":true},{"actual":4.0,"check":"empty zero stratum","expected":4,"passed":true},{"actual":null,"check":"unobserved positive stratum","expected":null,"passed":true},{"actual":0,"check":"empty frame","expected":0,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"disproportionate allocation\", \"actual\": 16.0, \"expected\": 16, \"passed\": true}, {\"check\": \"single stratum expansion\", \"actual\": 16.0, \"expected\": 16, \"passed\": true}, {\"check\": \"census strata\", \"actual\": 7.0, \"expected\": 7, \"passed\": true}, {\"check\": \"empty zero stratum\", \"actual\": 4.0, \"expected\": 4, \"passed\": true}, {\"check\": \"unobserved positive stratum\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"empty frame\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}