{"abstract":"Normalizing inclusion weights changes a population total.","category":"Survey sampling estimators","checks":6,"contract":"Rows are (value, positive inclusion probability <= 1); return the estimated population total rounded to eight decimals; empty sample totals zero.","contract_signature":"rows","evaluation_group":"model-40b004a5fb11e1d0","failed_approach":"Multiplying the normalized mean by sample size still discards the inclusion-probability scale.","family":"z-survey_sampling-ht-total","id":"FA-12591","implementations":{"attempt":{"sha256":"ad32ab58de4db5053d3bf8eabeb3390fc57e13aeab457e846f1ab4a48172519c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    return round(len(rows)*sum(y/p for y,p in rows)/sum(1/p for y,p in rows),8) if rows else 0\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('unequal probabilities',solve([(N,0.5),(2*N,0.25)]),10*N)\ncheck('single expanded unit',solve([(3*N,0.25)]),12*N)\ncheck('census',solve([(N,1),(2*N,1)]),3*N)\ncheck('zero valued sampled unit',solve([(0,0.5),(N,0.5)]),2*N)\ncheck('signed contribution',solve([(-N,0.5),(N,1)]),-N)\ncheck('empty sample',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":"06c3c3a58f0c2cc092265d2cd66b440d27059163e6e3d0b213d0e441f6a228df","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows):\n    return round(sum(y/p for y,p in rows)/sum(1/p for y,p in rows),8) if rows else 0\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('unequal probabilities',solve([(N,0.5),(2*N,0.25)]),10*N)\ncheck('single expanded unit',solve([(3*N,0.25)]),12*N)\ncheck('census',solve([(N,1),(2*N,1)]),3*N)\ncheck('zero valued sampled unit',solve([(0,0.5),(N,0.5)]),2*N)\ncheck('signed contribution',solve([(-N,0.5),(N,1)]),-N)\ncheck('empty sample',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-ht-total","generated_at":"2026-09-29T14:38:58.192597+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.","root_cause":"A Horvitz-Thompson total is replaced by a normalized weighted mean.","sha256":"1b734c27ec944964896cfca2d0a257c88e05a062f9de66564a823da5728d88bc","title":"Normalizing inclusion weights changes a population total · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":43.58,"exit_code":1,"observations":[{"actual":3.33333333,"check":"unequal probabilities","expected":10,"passed":false},{"actual":3.0,"check":"single expanded unit","expected":12,"passed":false},{"actual":3.0,"check":"census","expected":3,"passed":true},{"actual":1.0,"check":"zero valued sampled unit","expected":2,"passed":false},{"actual":-0.66666667,"check":"signed contribution","expected":-1,"passed":false},{"actual":0,"check":"empty sample","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"unequal probabilities\", \"actual\": 3.33333333, \"expected\": 10, \"passed\": false}, {\"check\": \"single expanded unit\", \"actual\": 3.0, \"expected\": 12, \"passed\": false}, {\"check\": \"census\", \"actual\": 3.0, \"expected\": 3, \"passed\": true}, {\"check\": \"zero valued sampled unit\", \"actual\": 1.0, \"expected\": 2, \"passed\": false}, {\"check\": \"signed contribution\", \"actual\": -0.66666667, \"expected\": -1, \"passed\": false}, {\"check\": \"empty sample\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.123,"exit_code":1,"observations":[{"actual":1.66666667,"check":"unequal probabilities","expected":10,"passed":false},{"actual":3.0,"check":"single expanded unit","expected":12,"passed":false},{"actual":1.5,"check":"census","expected":3,"passed":false},{"actual":0.5,"check":"zero valued sampled unit","expected":2,"passed":false},{"actual":-0.33333333,"check":"signed contribution","expected":-1,"passed":false},{"actual":0,"check":"empty sample","expected":0,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"unequal probabilities\", \"actual\": 1.66666667, \"expected\": 10, \"passed\": false}, {\"check\": \"single expanded unit\", \"actual\": 3.0, \"expected\": 12, \"passed\": false}, {\"check\": \"census\", \"actual\": 1.5, \"expected\": 3, \"passed\": false}, {\"check\": \"zero valued sampled unit\", \"actual\": 0.5, \"expected\": 2, \"passed\": false}, {\"check\": \"signed contribution\", \"actual\": -0.33333333, \"expected\": -1, \"passed\": false}, {\"check\": \"empty sample\", \"actual\": 0, \"expected\": 0, \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}