Can two runners reach 12.43 mi together but have different prospects?

Only strata with at least 20 finishes in each of the three groups qualify. Use the smallest group count as each stratum’s 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 3.11, 6.21, 9.32, 12.43, 15.53, 18.64, 21.75, 24.85 and 26.22 mi. 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 3.22 and 32.19 minutes/mi. 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.

Marathons, years and recorded data. Chart samples may be smaller than the eligible analysis cohort.