{ "schema_version": 1, "id": "ext_pace_trend_at_20k", "question_id": "r03_accel_vs_decel_20k", "title": "Can two runners reach 20 km together but have different prospects?", "status": "ready", "as_of": "2026-09-12T14:12:22Z", "n": 1920435, "input_export_id": "private-20260912-0934", "input_as_of": "2026-09-12T13:37:16Z", "live_json_as_of": "2026-09-12T04:11:06Z", "input_asset_sha256": "cb4e0ab7432010de29755ec5d75ca3b370e64e481eda5b20c44b359f39552204", "input_manifest_sha256": "a6f534d40bac291e0a1bc2eeb70633660acd00a710a090320876736de9c30f4d", "analysis_script_sha256": "7c6959b427fa1b06bb9600bb3377ecb226257d14aa0ec61a71a63f42bc87a3dd", "analysis_version": 1, "engine": "DuckDB 1.4.4", "corpus": { "n_records": 4462379, "n_cities": 34, "n_race_years": 256 }, "cohort": { "deduplicated": 4462379, "complete": 3830211, "increasing": 3604993, "timing_eligible": 3595426, "eligible": 3517336, "source_quality_excluded": 78090, "raw": 4462379, "duplicates_removed": 0, "missing_or_unparsed": 632168, "non_increasing": 225218, "outside_quality_bounds": 9567 }, "methodology_prose": [ "Compare the 15\u201320 km pace with 10\u201315 km. Accelerating is more than 2% faster, slowing more than 2% slower, and steady within 2%. Match within city, year, race and the same floored minute of elapsed time at 20 km.", "Only strata with at least 20 finishes in each of the three groups qualify. Use the smallest group count as each stratum\u2019s common weight for all three groups, then average the within-stratum finish-time differences versus steady. Sample counts are actual observations, not matching weights.", "Runners arrive within the same 60-second band, not at an identical instant. Prior fitness and runner intention are unknown. This is a conditional association, not proof that accelerating causes a better finish or an out-of-sample prediction.", "Use complete, strictly increasing elapsed checkpoints at 5, 10, 15, 20, 25, 30, 35, 40 and 42.195 km. Clock strings must parse as H:MM:SS or M:SS. No missing splits are interpolated.", "Remove exact duplicate race records, ignoring database IDs, ingestion timestamps and source URLs. Retain finishes from 90 minutes to 12 hours with every section between 2 and 20 minutes per km. These quality filters can exclude genuine unusual performances; the analysis describes this eligible cohort, not every entrant.", "Each observation is a race finish. The same person can appear in multiple races. No runner identities are linked across races. Public cells require at least 100 observations; matched comparisons additionally require at least 20 per group in each stratum.", "Apply the reviewed source-quality edition exclusions for this exact export after the timing checks. Known invalid split grids, incomplete ingestion, unreconciled HOLD editions and a selected top-finisher field do not contribute to the analyses or prior benchmarks. Report source exclusions separately; an already invalid timing row is not counted twice. Missing age or recorded gender alone does not exclude an otherwise eligible finish from the overall cohort. Other sparse editions are not declared incomplete merely from their size." ], "observational": true, "minimum_public_cell": 100, "source_quality": { "version": 1, "release_tag": "private-export-20260912-0934", "reviewed_edition_policy": true, "editions": [ { "city": "Honolulu", "year": 2016, "category": "invalid_split_grid", "reason": "Producer explicitly force-dropped this incomplete 5 km grid.", "raw_records": 20118, "deduplicated_records": 20118, "timing_eligible_excluded": 0 }, { "city": "Rotterdam", "year": 2012, "category": "invalid_split_grid", "reason": "Producer explicitly force-dropped this incomplete 5 km grid.", "raw_records": 7542, "deduplicated_records": 7542, "timing_eligible_excluded": 0 }, { "city": "Eindhoven", "year": 2009, "category": "invalid_split_grid", "reason": "Producer explicitly force-dropped this incomplete 5 km grid.", "raw_records": 1407, "deduplicated_records": 1407, "timing_eligible_excluded": 0 }, { "city": "Eindhoven", "year": 2010, "category": "invalid_split_grid", "reason": "Producer explicitly force-dropped this incomplete 5 km grid.", "raw_records": 1462, "deduplicated_records": 1462, "timing_eligible_excluded": 0 }, { "city": "Frankfurt", "year": 2019, "category": "invalid_split_grid", "reason": "Producer explicitly force-dropped this 5 km grid; numerically plausible rows are not reinstated.", "raw_records": 12513, "deduplicated_records": 12513, "timing_eligible_excluded": 10624 }, { "city": "New York", "year": 2008, "category": "unreconciled_hold", "reason": "Previously partial ingestion has grown to 38,047 records, but source-total reconciliation and explicit completion evidence are absent; keep the prior hold pending review.", "raw_records": 38047, "deduplicated_records": 38047, "timing_eligible_excluded": 37387 }, { "city": "Chicago", "year": 2016, "category": "incomplete_ingestion", "reason": "Producer handoff identifies this 6,512-record edition as incomplete and on HOLD.", "raw_records": 6512, "deduplicated_records": 6512, "timing_eligible_excluded": 6506 }, { "city": "Tokyo", "year": 2026, "category": "selected_field", "reason": "Source notes identify top-500 PDFs, not a representative full marathon field.", "raw_records": 353, "deduplicated_records": 353, "timing_eligible_excluded": 353 }, { "city": "Amsterdam", "year": 2025, "category": "unreconciled_hold", "reason": "Source audit marks HOLD: 23,328 listed versus 23,325 retrieved. This conservative hold does not establish a large bias from the three missing records.", "raw_records": 23325, "deduplicated_records": 23325, "timing_eligible_excluded": 23220 }, { "city": "Valencia", "year": 2017, "category": "incomplete_ingestion", "reason": "Source audit marks HOLD: 3,373 listed detail pages missing; the observed records also lack 20 km.", "raw_records": 12485, "deduplicated_records": 12485, "timing_eligible_excluded": 0 }, { "city": "Valencia", "year": 2018, "category": "incomplete_ingestion", "reason": "Producer handoff retains an incomplete/HOLD status; the edition also lacks the observed 20 km checkpoint.", "raw_records": 19236, "deduplicated_records": 19236, "timing_eligible_excluded": 0 } ], "policy_sha256": "c08e83c993025dc41c0344be7b5442d74b3fb0588c38949481d5bc0a08f45fa0", "script_sha256": "433e8b9566b5afd809f4de1180fab222e63ad40678a33f6c93f08712cf820c77" }, "source_quality_script_sha256": "433e8b9566b5afd809f4de1180fab222e63ad40678a33f6c93f08712cf820c77" }