{ "schema_version": "forecast-artifact.v1", "run": { "run_id": "2026-08-24T20-35-00-04-00__m0.2.0__de273d100cc8e", "status": "research_preview", "generated_at": "2026-08-24T20:35:00-04:00", "data_cutoff": "2026-08-24T20:10:00-04:00", "election_date": "2026-11-03", "timezone": "America/Detroit", "days_to_election": 71, "model_version": "0.2.0", "methodology_version": "generic-polling-0.2", "data_version": "e273d100cc8e", "simulation_count": 40000, "random_seed": 2026082404, "validation_state": "research_preview", "model_kind": "polling_only_research_preview" }, "candidates": [ { "candidate_id": "jocelyn_benson", "name": "Jocelyn Benson", "party": "Democratic", "role": "democratic_nominee", "is_aggregate": false }, { "candidate_id": "john_james", "name": "John James", "party": "Republican", "role": "republican_nominee", "is_aggregate": false }, { "candidate_id": "other_candidates", "name": "Other candidates", "party": "Other", "role": "aggregate_remainder", "is_aggregate": true } ], "views": { "nowcast": { "label": "If voting ended today", "leader_candidate_id": "jocelyn_benson", "candidates": [ { "candidate_id": "jocelyn_benson", "name": "Jocelyn Benson", "party": "Democratic", "is_aggregate": false, "win_probability": 0.98655, "vote_share": { "median": 52.6455, "mean": 52.6464, "interval_50": { "lower": 51.4208, "upper": 53.8673 }, "interval_80": { "lower": 50.3182, "upper": 54.9856 } } }, { "candidate_id": "john_james", "name": "John James", "party": "Republican", "is_aggregate": false, "win_probability": 0.01345, "vote_share": { "median": 45.2764, "mean": 45.2905, "interval_50": { "lower": 44.0797, "upper": 46.498 }, "interval_80": { "lower": 43.0374, "upper": 47.5857 } } }, { "candidate_id": "other_candidates", "name": "Other candidates", "party": "Other", "is_aggregate": true, "win_probability": null, "win_probability_status": "not_modeled", "vote_share": { "median": 2.0011, "mean": 2.0631, "interval_50": { "lower": 0.9805, "upper": 3.0229 }, "interval_80": { "lower": 0.0661, "upper": 3.9297 } } } ], "probability_scope": "conditional_on_one_of_the_two_modeled_major_candidates_winning", "major_candidate_margin": { "median": 7.3706, "mean": 7.3559, "interval_50": { "lower": 5.1138, "upper": 9.5908 }, "interval_80": { "lower": 3.0962, "upper": 11.5999 } }, "normalized_two_candidate_margin": { "median": 7.5351, "mean": 7.511, "interval_50": { "lower": 5.2188, "upper": 9.7943 }, "interval_80": { "lower": 3.1616, "upper": 11.8366 } }, "margin_convention": "Positive values indicate Jocelyn Benson leads; negative values indicate John James leads." }, "election_forecast": { "label": "Election-day forecast", "leader_candidate_id": "jocelyn_benson", "candidates": [ { "candidate_id": "jocelyn_benson", "name": "Jocelyn Benson", "party": "Democratic", "is_aggregate": false, "win_probability": 0.89965, "vote_share": { "median": 52.5857, "mean": 52.5796, "interval_50": { "lower": 50.5716, "upper": 54.5688 }, "interval_80": { "lower": 48.7044, "upper": 56.4431 } } }, { "candidate_id": "john_james", "name": "John James", "party": "Republican", "is_aggregate": false, "win_probability": 0.10035, "vote_share": { "median": 45.2309, "mean": 45.2395, "interval_50": { "lower": 43.2584, "upper": 47.2051 }, "interval_80": { "lower": 41.4024, "upper": 49.0807 } } }, { "candidate_id": "other_candidates", "name": "Other candidates", "party": "Other", "is_aggregate": true, "win_probability": null, "win_probability_status": "not_modeled", "vote_share": { "median": 2.0202, "mean": 2.1809, "interval_50": { "lower": 0.6881, "upper": 3.3465 }, "interval_80": { "lower": 0.0, "upper": 4.5658 } } } ], "probability_scope": "conditional_on_one_of_the_two_modeled_major_candidates_winning", "major_candidate_margin": { "median": 7.3497, "mean": 7.34, "interval_50": { "lower": 3.5745, "upper": 11.0775 }, "interval_80": { "lower": -0.0177, "upper": 14.7261 } }, "normalized_two_candidate_margin": { "median": 7.51, "mean": 7.5044, "interval_50": { "lower": 3.6501, "upper": 11.336 }, "interval_80": { "lower": -0.0181, "upper": 15.0252 } }, "margin_convention": "Positive values indicate Jocelyn Benson leads; negative values indicate John James leads." } }, "components": { "polls": { "available": true, "normalized_two_candidate_margin": { "median": 7.5351, "mean": 7.511, "interval_50": { "lower": 5.2188, "upper": 9.7943 }, "interval_80": { "lower": 3.1616, "upper": 11.8366 } }, "accepted_count": 4, "distinct_pollsters": 4, "effective_poll_count": 3.4725 }, "historical_reference": { "available": true, "normalized_two_candidate_margin": { "median": 4.662, "mean": 4.662, "interval_50": { "lower": 4.662, "upper": 4.662 }, "interval_80": { "lower": 4.662, "upper": 4.662 } }, "forecast_effect": 0 }, "combined": { "available": true, "normalized_two_candidate_margin": { "median": 7.51, "mean": 7.5044, "interval_50": { "lower": 3.6501, "upper": 11.336 }, "interval_80": { "lower": -0.0181, "upper": 15.0252 } }, "poll_influence": 1.0, "historical_reference_influence": 0.0, "historical_error_calibration": { "algorithm_version": "weighted-poll-baseline-0.1.0", "implementation_version": "production-poll-aggregation-backtest-0.3.0", "scope": "Out-of-time production-aggregator polling error by days before Election Day. This calibrates the polls-only baseline and does not validate the full fundamentals model.", "selected_horizon_days": 60, "selected_stratum": "robust_polling", "race_count": 21, "mae": 5.5537, "rmse": 6.2599, "error_sd": 6.3333, "central_80_error": [ -8.7387, 7.3942 ] }, "error_distribution": "student_t", "error_degrees_of_freedom": 7.0 }, "election_rule": { "rule": "plurality", "runoff_probability": 0.0, "treatment": "The named candidate with the most simulated votes wins the draw." } }, "bridge": [ { "stage_id": "previous_governor_result", "label": "Certified 2022 governor result", "description": "Gretchen Whitmer versus Tudor Dixon, shown only as a statewide historical comparison.", "normalized_two_candidate_margin": { "median": 10.7724, "mean": 10.7724, "interval_50": { "lower": 10.7724, "upper": 10.7724 }, "interval_80": { "lower": 10.7724, "upper": 10.7724 } }, "candidate_vote_shares": { "jocelyn_benson": 54.5, "john_james": 43.9, "other_candidates": 1.6 }, "source_ids": [ "mi_sos_2022_governor" ], "forecast_effect": 0, "is_model_estimate": false }, { "stage_id": "presidential_2024_result", "label": "Certified 2024 presidential result", "description": "Michigan's certified presidential vote, shown only as a recent statewide comparison.", "normalized_two_candidate_margin": { "median": -1.4484, "mean": -1.4484, "interval_50": { "lower": -1.4484, "upper": -1.4484 }, "interval_80": { "lower": -1.4484, "upper": -1.4484 } }, "candidate_vote_shares": { "jocelyn_benson": 48.31, "john_james": 49.73, "other_candidates": 1.96 }, "source_ids": [ "fec_2024_president" ], "forecast_effect": 0, "is_model_estimate": false }, { "stage_id": "structural_2026", "label": "Historical reference midpoint", "description": "The midpoint of the certified governor and presidential two-party margins. It is a descriptive comparison with exactly zero separate forecast effect.", "normalized_two_candidate_margin": { "median": 4.662, "mean": 4.662, "interval_50": { "lower": 4.662, "upper": 4.662 }, "interval_80": { "lower": 4.662, "upper": 4.662 } }, "forecast_effect": 0, "is_model_estimate": false }, { "stage_id": "current_polls", "label": "Current polls", "description": "Quality-, recency-, sponsor-, and correlation-adjusted estimate from reviewed polls.", "normalized_two_candidate_margin": { "median": 7.5351, "mean": 7.511, "interval_50": { "lower": 5.2188, "upper": 9.7943 }, "interval_80": { "lower": 3.1616, "upper": 11.8366 } }, "available": true, "is_model_estimate": true }, { "stage_id": "november_forecast", "label": "Election Day forecast", "description": "The current polling center with uncertainty set by the nearest out-of-time gubernatorial polling-error calibration; historical reference results add no points.", "normalized_two_candidate_margin": { "median": 7.51, "mean": 7.5044, "interval_50": { "lower": 3.6501, "upper": 11.336 }, "interval_80": { "lower": -0.0181, "upper": 15.0252 } }, "is_model_estimate": true } ], "bridge_diagnostics": null, "polls": [ { "poll_id": "2026-08-11-aarp-benson-james", "pollster": "Fabrizio Ward / Impact Research", "sponsor": "AARP Michigan", "partisan_sponsor": null, "field_start": "2026-08-09", "field_end": "2026-08-11", "published_at": "2026-08-20T23:59:59.999999-04:00", "population": "LV", "sample_size": 877, "sample_size_disclosed": true, "mode": "Mixed live telephone and SMS-to-web", "raw": { "jocelyn_benson": 49.0, "john_james": 44.0, "other": null, "undecided": 7.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 5.376344, "adjusted_two_candidate_margin": 5.376344, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.0, "quality_multiplier": 0.7125, "recency_multiplier": 0.72483, "sampling_sd": 3.371876, "review_status": "accepted", "review_note": "Original bipartisan release and methodology reviewed; random voter-list sample with live telephone and SMS-to-web interviewing; other-candidate share was not separately reported.", "source_id": "mi_aarp_august_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.351666, "model_use": { "included": true, "reason": "Included under the generic polling-only research-preview rules." } }, { "poll_id": "2026-08-10-tipp-benson-james", "pollster": "TIPP Insights", "sponsor": "League of American Workers", "partisan_sponsor": "R", "field_start": "2026-08-06", "field_end": "2026-08-10", "published_at": "2026-08-18T23:59:59.999999-04:00", "population": "LV", "sample_size": 1215, "sample_size_disclosed": true, "mode": "Online panel", "raw": { "jocelyn_benson": 53.0, "john_james": 37.0, "other": null, "undecided": 10.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 17.777778, "adjusted_two_candidate_margin": 18.577778, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.8, "quality_multiplier": 0.286875, "recency_multiplier": 0.707107, "sampling_sd": 2.823177, "review_status": "accepted_with_penalty", "review_note": "Original sponsor release reviewed. Apply a Republican-aligned sponsor and online-panel penalty; other-candidate share was not separately reported.", "source_id": "mi_tipp_august_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.19704, "model_use": { "included": true, "reason": "Included under the generic polling-only research-preview rules." } }, { "poll_id": "2026-08-10-fox-benson-james", "pollster": "Beacon Research / Shaw & Company Research", "sponsor": "Fox News", "partisan_sponsor": null, "field_start": "2026-08-06", "field_end": "2026-08-10", "published_at": "2026-08-13T23:59:59.999999-04:00", "population": "RV", "sample_size": 1006, "sample_size_disclosed": true, "mode": "Mixed live telephone and SMS-to-web", "raw": { "jocelyn_benson": 52.0, "john_james": 47.0, "other": null, "undecided": 1.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 5.050505, "adjusted_two_candidate_margin": 5.050505, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.0, "quality_multiplier": 0.605625, "recency_multiplier": 0.707107, "sampling_sd": 3.14881, "review_status": "accepted", "review_note": "Original topline reviewed. Random Michigan voter-file sample with live telephone and SMS-to-web interviews; registered-voter population multiplier applies and other-candidate share was not separately reported.", "source_id": "mi_fox_august_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.334386, "model_use": { "included": true, "reason": "Included under the generic polling-only research-preview rules." } }, { "poll_id": "2026-07-29-mitchell-benson-james", "pollster": "Mitchell Research", "sponsor": "Mitchell Research", "partisan_sponsor": null, "field_start": "2026-07-28", "field_end": "2026-07-29", "published_at": "2026-07-31T23:59:59.999999-04:00", "population": "LV", "sample_size": 672, "sample_size_disclosed": true, "mode": "Mixed telephone and online", "raw": { "jocelyn_benson": 46.0, "john_james": 44.0, "other": null, "undecided": 10.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 2.222222, "adjusted_two_candidate_margin": 2.222222, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.0, "quality_multiplier": 0.4275, "recency_multiplier": 0.525378, "sampling_sd": 3.856631, "review_status": "accepted_with_penalty", "review_note": "Original release reviewed. Candidate order and complete frame and weighting details are not disclosed, so a quality penalty applies; other-candidate share was not separately reported.", "source_id": "mi_mitchell_july_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.116908, "model_use": { "included": true, "reason": "Included under the generic polling-only research-preview rules." } } ], "poll_ledger": [ { "poll_id": "2026-08-11-aarp-benson-james", "pollster": "Fabrizio Ward / Impact Research", "sponsor": "AARP Michigan", "partisan_sponsor": null, "field_start": "2026-08-09", "field_end": "2026-08-11", "published_at": "2026-08-20T23:59:59.999999-04:00", "population": "LV", "sample_size": 877, "sample_size_disclosed": true, "mode": "Mixed live telephone and SMS-to-web", "raw": { "jocelyn_benson": 49.0, "john_james": 44.0, "other": null, "undecided": 7.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 5.376344, "adjusted_two_candidate_margin": 5.376344, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.0, "quality_multiplier": 0.7125, "recency_multiplier": 0.72483, "sampling_sd": 3.371876, "review_status": "accepted", "review_note": "Original bipartisan release and methodology reviewed; random voter-list sample with live telephone and SMS-to-web interviewing; other-candidate share was not separately reported.", "source_id": "mi_aarp_august_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.351666, "model_use": { "included": true, "reason": "Included in the current polling average." } }, { "poll_id": "2026-08-10-tipp-benson-james", "pollster": "TIPP Insights", "sponsor": "League of American Workers", "partisan_sponsor": "R", "field_start": "2026-08-06", "field_end": "2026-08-10", "published_at": "2026-08-18T23:59:59.999999-04:00", "population": "LV", "sample_size": 1215, "sample_size_disclosed": true, "mode": "Online panel", "raw": { "jocelyn_benson": 53.0, "john_james": 37.0, "other": null, "undecided": 10.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 17.777778, "adjusted_two_candidate_margin": 18.577778, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.8, "quality_multiplier": 0.286875, "recency_multiplier": 0.707107, "sampling_sd": 2.823177, "review_status": "accepted_with_penalty", "review_note": "Original sponsor release reviewed. Apply a Republican-aligned sponsor and online-panel penalty; other-candidate share was not separately reported.", "source_id": "mi_tipp_august_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.19704, "model_use": { "included": true, "reason": "Included in the current polling average." } }, { "poll_id": "2026-08-10-fox-benson-james", "pollster": "Beacon Research / Shaw & Company Research", "sponsor": "Fox News", "partisan_sponsor": null, "field_start": "2026-08-06", "field_end": "2026-08-10", "published_at": "2026-08-13T23:59:59.999999-04:00", "population": "RV", "sample_size": 1006, "sample_size_disclosed": true, "mode": "Mixed live telephone and SMS-to-web", "raw": { "jocelyn_benson": 52.0, "john_james": 47.0, "other": null, "undecided": 1.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 5.050505, "adjusted_two_candidate_margin": 5.050505, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.0, "quality_multiplier": 0.605625, "recency_multiplier": 0.707107, "sampling_sd": 3.14881, "review_status": "accepted", "review_note": "Original topline reviewed. Random Michigan voter-file sample with live telephone and SMS-to-web interviews; registered-voter population multiplier applies and other-candidate share was not separately reported.", "source_id": "mi_fox_august_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.334386, "model_use": { "included": true, "reason": "Included in the current polling average." } }, { "poll_id": "2026-07-29-mitchell-benson-james", "pollster": "Mitchell Research", "sponsor": "Mitchell Research", "partisan_sponsor": null, "field_start": "2026-07-28", "field_end": "2026-07-29", "published_at": "2026-07-31T23:59:59.999999-04:00", "population": "LV", "sample_size": 672, "sample_size_disclosed": true, "mode": "Mixed telephone and online", "raw": { "jocelyn_benson": 46.0, "john_james": 44.0, "other": null, "undecided": 10.0 }, "other_share_disclosed": false, "raw_two_candidate_margin": 2.222222, "adjusted_two_candidate_margin": 2.222222, "other_decided_share": 0.0, "house_effect_adjustment": -0.0, "sponsorship_adjustment": 0.0, "quality_multiplier": 0.4275, "recency_multiplier": 0.525378, "sampling_sd": 3.856631, "review_status": "accepted_with_penalty", "review_note": "Original release reviewed. Candidate order and complete frame and weighting details are not disclosed, so a quality penalty applies; other-candidate share was not separately reported.", "source_id": "mi_mitchell_july_2026", "question_text": "If the election for governor were held today, for whom would you vote?", "normalized_weight": 0.116908, "model_use": { "included": true, "reason": "Included in the current polling average." } } ], "poll_exclusions": [], "poll_trend": [ { "date": "2026-07-29", "poll_id": "2026-07-29-mitchell-benson-james", "adjusted_two_candidate_margin": 2.222222, "other_decided_share": 0.0, "weight": 0.116908 }, { "date": "2026-08-10", "poll_id": "2026-08-10-fox-benson-james", "adjusted_two_candidate_margin": 5.050505, "other_decided_share": 0.0, "weight": 0.334386 }, { "date": "2026-08-10", "poll_id": "2026-08-10-tipp-benson-james", "adjusted_two_candidate_margin": 18.577778, "other_decided_share": 0.0, "weight": 0.19704 }, { "date": "2026-08-11", "poll_id": "2026-08-11-aarp-benson-james", "adjusted_two_candidate_margin": 5.376344, "other_decided_share": 0.0, "weight": 0.351666 } ], "probability_history": [ { "date": "2026-08-24T20:35:00-04:00", "data_cutoff": "2026-08-24T20:10:00-04:00", "run_id": "2026-08-24T20-35-00-04-00__m0.2.0__de273d100cc8e", "model_version": "0.2.0", "data_version": "e273d100cc8e", "margin": 7.3497, "low": -0.0177, "high": 14.7261, "candidate_win_probabilities": { "jocelyn_benson": 0.89965, "john_james": 0.10035 }, "margin_basis": "all_ballot_major_candidate_margin", "probability_scope": "conditional_on_one_of_the_two_modeled_major_candidates_winning" } ], "evidence_ledger": [ { "event_id": "mi_2026_major_party_nominees", "event_at": "2026-08-04", "published_at": "2026-08-05", "headline": "Jocelyn Benson and John James win the Michigan governor nominations", "category": "candidate_field", "candidates": [ "jocelyn_benson", "john_james" ], "mechanism": "candidate_field", "status": "confirmed", "source_ids": [ "mi_primary_2026_ap", "mi_candidate_field_2026" ], "summary": "The Democratic and Republican nominees are set for the open-seat general election.", "model_treatment": { "type": "defined_input_update", "effect": "Set the two modeled major candidates; do not transfer the term-limited incumbent's prior result." } }, { "event_id": "mi_2026_duggan_withdrawal", "event_at": "2026-05-21", "published_at": "2026-05-21", "headline": "Mike Duggan ends his independent campaign for governor", "category": "candidate_field", "candidates": [ "other_candidates" ], "mechanism": "candidate_field", "status": "confirmed", "source_ids": [ "mi_duggan_withdrawal_2026" ], "summary": "Duggan's withdrawal removes the best-known independent candidacy from the current field.", "model_treatment": { "type": "monitor_only", "effect": "Do not model Duggan as a candidate; retain a generic aggregate remainder for any final minor candidates." } }, { "event_id": "mi_2026_august_polling", "event_at": "2026-08-11", "published_at": "2026-08-20", "headline": "Post-primary Michigan surveys show Benson ahead of James", "category": "qualifying_poll", "candidates": [ "jocelyn_benson", "john_james" ], "mechanism": "polling_evidence", "status": "confirmed", "source_ids": [ "mi_aarp_august_2026", "mi_tipp_august_2026", "mi_fox_august_2026" ], "summary": "Three August surveys report Benson leads of varying size, with sponsor, population, and mode differences handled by the aggregator.", "model_treatment": { "type": "poll_record", "effect": "Include through the documented poll-quality, sponsor, recency, and correlation controls." } } ], "context_signals": [], "context_assessments": { "schema_version": "context-assessments.v1", "race_id": "michigan-governor-2026", "status": "reviewed", "as_of": "2026-08-24", "model_status": "commentary_only", "forecast_effect": 0, "assessment_count": 2, "assessments": [ { "id": "mi_state_control_stakes", "family": "state_control", "direction": "neutral", "target_candidate_id": null, "confidence": "high", "observed_evidence": { "summary": "Michigan currently has a Democratic governor and Senate alongside a Republican House, so state government is divided.", "evidence_source_ids": [ "mi_state_control_2026" ], "current_signal_ids": [], "related_sample_ids": [] }, "analyst_inference": { "mechanism": "The open-seat governor result will determine the executive veto, appointments, and agency direction while legislative control is decided separately.", "interpretation": "The race can preserve a Democratic executive check or install a Republican governor during a period of divided legislative control.", "counterweight_or_caveat": "Concurrent chamber results could change the final governing arrangement, and control stakes are not evidence of voter preference.", "what_would_change_this": "Certified chamber results would establish the post-election control configuration." }, "model_status": "commentary_only", "forecast_effect": 0, "dependency_group": "mi_state_control_2026", "overlaps_model_component": [], "double_count_warning": "Political consequences are commentary only and add exactly zero forecast points.", "cadence": "on_control_change", "status": "active", "as_of": "2026-08-24" }, { "id": "mi_open_seat_transition", "family": "candidate_field", "direction": "neutral", "target_candidate_id": null, "confidence": "high", "observed_evidence": { "summary": "The sitting governor is term-limited, Jocelyn Benson and John James won their party nominations, and Mike Duggan ended his independent campaign before the primary.", "evidence_source_ids": [ "mi_primary_2026_ap", "mi_candidate_field_2026", "mi_duggan_withdrawal_2026" ], "current_signal_ids": [], "related_sample_ids": [] }, "analyst_inference": { "mechanism": "An open seat removes direct incumbent continuity and makes candidate-specific polling the central current signal.", "interpretation": "The model does not transfer Gretchen Whitmer's 2022 result to Benson; that result is displayed only as history.", "counterweight_or_caveat": "Additional general-election candidates or ballot changes could alter the aggregate remainder.", "what_would_change_this": "A certified final candidate list and repeated full-field surveys would refine the field treatment." }, "model_status": "commentary_only", "forecast_effect": 0, "dependency_group": "mi_candidate_field_2026", "overlaps_model_component": [ "historical_reference" ], "double_count_warning": "The open-seat distinction prevents transfer of the prior governor result and adds no separate margin points.", "cadence": "on_certification", "status": "active", "as_of": "2026-08-24" } ] }, "accuracy": { "status": "research_preview", "probability_label": "polling-only research preview", "modeled_poll_count": 4, "distinct_pollsters": 4, "context_signal_count": 0, "context_signal_forecast_effect": 0, "context_assessment_count": 2, "context_assessment_forecast_effect": 0, "calibration_algorithm_version": "weighted-poll-baseline-0.1.0", "calibration_implementation_version": "production-poll-aggregation-backtest-0.3.0", "calibration_scope": "Out-of-time production-aggregator polling error by days before Election Day. This calibrates the polls-only baseline and does not validate the full fundamentals model.", "backtest_snapshots": [ { "days_before_election": 30, "series": "robust_polling", "race_count": 37, "mae": 5.5841, "rmse": 6.629, "error_sd": 6.7135, "central_80_error": [ -10.3472, 7.4356 ] }, { "days_before_election": 1, "series": "robust_polling", "race_count": 43, "mae": 4.793, "rmse": 5.9338, "error_sd": 5.9744, "central_80_error": [ -7.5576, 7.6031 ] } ], "layers": [ { "layer_id": "candidate_field", "label": "Major-party candidate field", "status": "major_party_nominees_set_general_field_provisional", "summary": "Jocelyn Benson and John James won their major-party primaries. Mike Duggan ended his independent campaign in May; the complete November ballot remains provisional." }, { "layer_id": "historical_reference", "label": "Certified historical reference", "status": "descriptive_only", "summary": "The prior governor and presidential results are displayed for context and add zero forecast points." }, { "layer_id": "poll_aggregation", "label": "Poll aggregation", "status": "historically_backtested", "summary": "Reviewed polls use the same recency, quality, sponsor, and pollster-correlation controls as the archived backtest." }, { "layer_id": "directional_context", "label": "Reviewed directional context", "status": "commentary_only", "summary": "2 reviewed assessments explain direction and caveats with exactly zero forecast effect." }, { "layer_id": "combined_probability", "label": "Polling-only win probability", "status": "end_to_end_backtest_pending", "summary": "The error layer is historically calibrated; the full race-specific publication remains a research preview." } ] }, "data_quality": { "grade": "C", "label": "preliminary", "score": 78, "poll_count": 4, "distinct_pollsters": 4, "fundamental_feature_count": 0, "candidate_field_status": "major_party_nominees_set_general_field_provisional", "warnings": [ { "code": "polling_only_research_preview", "severity": "warning", "message": "This expansion forecast is centered on reviewed polling. Certified historical results are descriptive reference points and have no separate forecast effect." }, { "code": "combined_model_backtest_pending", "severity": "warning", "message": "The polling-error layer is historically calibrated, but this race-specific publication has not completed an end-to-end out-of-sample validation cycle." }, { "code": "context_assessments_commentary_only", "severity": "info", "message": "2 reviewed context assessment(s) have exactly zero forecast effect." }, { "code": "michigan_open_seat_polling_only", "severity": "warning", "message": "This is an open seat. Gretchen Whitmer's 2022 result is descriptive only and is not transferred to Jocelyn Benson." } ] }, "sources": [ { "source_id": "mi_primary_2026_ap", "title": "Michigan 2026 primary election results", "publisher": "Associated Press / NPR", "canonical_url": "https://apps.npr.org/primary-election-results-2026/states/MI.html", "source_type": "primary_results_report", "authority_tier": 2 }, { "source_id": "mi_candidate_field_2026", "title": "Michigan 2026 candidate listing", "publisher": "Michigan Bureau of Elections", "canonical_url": "https://mi-boe.entellitrak.com/etk-mi-boe-prod/page.request.do?electionType=PRI&electionYear=2026&page=page.miboePublicReport", "source_type": "official_candidate_list", "authority_tier": 1 }, { "source_id": "mi_aarp_august_2026", "title": "2026 midterm election poll — Michigan", "publisher": "AARP Research", "canonical_url": "https://www.aarp.org/pri/topics/voter-research/politics/2026-midterm-election-poll-michigan/", "source_type": "poll_release", "authority_tier": 2 }, { "source_id": "mi_tipp_august_2026", "title": "League of American Workers survey — Michigan", "publisher": "TIPP Insights", "canonical_url": "https://tippinsights.com/league-of-american-workers-survey-michigan-2/", "source_type": "poll_release", "authority_tier": 2 }, { "source_id": "mi_fox_august_2026", "title": "Fox News Michigan survey — August 2026", "publisher": "Fox News / Beacon Research / Shaw & Company Research", "canonical_url": "https://static.foxnews.com/foxnews.com/content/uploads/2026/08/fox_august-6-10-2026_michigan_topline_august-13-release.pdf", "source_type": "poll_questionnaire_topline", "authority_tier": 2 }, { "source_id": "mi_mitchell_july_2026", "title": "Michigan November election poll", "publisher": "Mitchell Research", "canonical_url": "https://static1.squarespace.com/static/5f14ae6fb2a20e01e9c6d608/t/6a6d26262f442f133d15fa49/1785538087149/MITCHELL%2BMI%2BPoll%2BNov%2BElectio%2BPress%2BRelease%2B7-31-2026%2B305PM_A.pdf", "source_type": "poll_release", "authority_tier": 3 }, { "source_id": "mi_sos_2022_governor", "title": "Michigan election results and data", "publisher": "Michigan Department of State", "canonical_url": "https://www.michigan.gov/sos/elections/election-results-and-data", "source_type": "certified_election_result", "authority_tier": 1 }, { "source_id": "fec_2024_president", "title": "Official 2024 presidential general election results", "publisher": "Federal Election Commission", "canonical_url": "https://www.fec.gov/documents/5644/2024presgeresults.pdf", "source_type": "certified_election_result", "authority_tier": 1 }, { "source_id": "mi_duggan_withdrawal_2026", "title": "Duggan ends campaign for Michigan governor", "publisher": "Michigan Public", "canonical_url": "https://www.michiganpublic.org/politics-government/2026-05-21/duggan-ends-campaign-for-michigan-governor", "source_type": "candidate_field_report", "authority_tier": 2 }, { "source_id": "mi_state_control_2026", "title": "2026 governors and legislatures", "publisher": "MultiState", "canonical_url": "https://www.multistate.us/resources/2026-governors-and-legislatures", "source_type": "state_control_reference", "authority_tier": 2 } ], "movements": [], "net_change_label": null, "reproducibility": { "input_hashes": { "config": "de8bc04c431fccbcf36ca62e0e27200b814468100d375283c78ceb90bd99993e", "polls": "1bb20a078d61c4d502f61bc91dea170b188494aed97baea5aa9c06ad6c755c9a", "sources": "4352c98d32b5ab86cdd84f9666c21a2edac631697adee6df780896e9679876f2", "context_assessments": "85915b3b964d6be3378b242e6655cfc32096a8c076d90080f55125ddea33075e", "events": "f0451a22734a4b9c6abfe79cd65c445468b0b8b55af2b376e73939f6fa379608", "calibration": "dadb6e0053f3399a841ee3b6b5cccaee0868c875288d11530e324beb5acbb2c2" }, "source_manifest_sha256": "4352c98d32b5ab86cdd84f9666c21a2edac631697adee6df780896e9679876f2", "code_revision": "5c5e61b57d2b7343a52c1333c5fccfe361b969bd", "configuration": { "schema_version": "generic-governor-model.v1", "race_id": "michigan-governor-2026", "model_kind": "polling_only_research_preview", "model_version": "0.2.0", "methodology_version": "generic-polling-0.2", "candidate_field_status": "major_party_nominees_set_general_field_provisional", "candidate_field_summary": "Jocelyn Benson and John James won their major-party primaries. Mike Duggan ended his independent campaign in May; the complete November ballot remains provisional.", "election": { "name": "2026 Michigan gubernatorial election", "date": "2026-11-03", "timezone": "America/Detroit", "rule": "plurality" }, "simulation": { "count": 40000, "seed": 2026082404 }, "candidates": [ { "candidate_id": "jocelyn_benson", "name": "Jocelyn Benson", "party": "Democratic", "role": "democratic_nominee" }, { "candidate_id": "john_james", "name": "John James", "party": "Republican", "role": "republican_nominee" }, { "candidate_id": "other_candidates", "name": "Other candidates", "party": "Other", "role": "aggregate_remainder", "is_aggregate": true } ], "reference_results": [ { "stage_id": "previous_governor_result", "label": "Certified 2022 governor result", "description": "Gretchen Whitmer versus Tudor Dixon, shown only as a statewide historical comparison.", "democratic_share": 54.5, "republican_share": 43.9, "other_share": 1.6, "source_ids": [ "mi_sos_2022_governor" ] }, { "stage_id": "presidential_2024_result", "label": "Certified 2024 presidential result", "description": "Michigan's certified presidential vote, shown only as a recent statewide comparison.", "democratic_share": 48.31, "republican_share": 49.73, "other_share": 1.96, "source_ids": [ "fec_2024_president" ] } ], "forecast": { "error_degrees_of_freedom": 7, "aggregate_share_fallback": 2.0 }, "model_warnings": [ { "code": "michigan_open_seat_polling_only", "severity": "warning", "message": "This is an open seat. Gretchen Whitmer's 2022 result is descriptive only and is not transferred to Jocelyn Benson." } ] }, "random_seed": 2026082404, "simulation_count": 40000, "artifact_hash_method": "SHA-256 of canonical JSON before reproducibility.artifact_sha256 is added", "artifact_sha256": "ee313ff5821b752ca9f52df4906ec674de88ab0d0b03beeb295270345e4a0d32" } }