Young marathon chasers stepping up to 3m4f+ for the first time carry the lift

Reasoning

Why this hypothesis exists: what the lab saw, the question it asked, the mechanism it proposed, what it predicted, and the result that would prove it wrong. Written before the test was run.

1. Observed
   • H175-young-horse-in-a-marathon-chase (H175: young horse in a marathon chase) was GREEN in the earlier research: A/E 1.16 on 618 bets (periods 1.17 / 1.21 / 1.05); now PROMISING. O-f49a1279
2. AskedIs the young-stayer lift carried by horses that have not yet run at 3m4f+ (stepping up in trip), as the 'market doubts unproven stamina' mechanism requires? answered
3. MechanismYoung chasers are often still improving and have more stamina than their form at shorter trips shows. Punters and layers lean on the belief that a marathon needs a seasoned horse, so a young horse stepping up in trip is doubted most.
4. Why the market misses itThe form book shows only runs at shorter trips, often finishing one-paced or beaten. Those runs make the horse look short of stamina at exactly the moment the longer trip suits it.
5. Predictedpositive, A/E 1.15 to 1.30 on 250+ bets, above young runners already raced at 3m4f+
6. Falsified ifA/E at or below 1.05, or no higher than young runners whose last run was already at 3m4f+
7. Rule sketchrace_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND distance_yards >= 6160 AND last_distance_yards < 6160

Mechanism and rationale

Young chasers are often still improving and have more stamina than their form at shorter trips shows. Punters and layers lean on the belief that a marathon needs a seasoned horse, so a young horse stepping up in trip is doubted most.

The rule

race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND distance_yards >= 6160 AND last_distance_yards < 6160

Reads: race_type, is_handicap, age, distance_yards, last_distance_yards

Pre-registration

Spec hash (sha256 of the canonical pre-spec)

c61a8d8d4ad9dc75c3e3de92c999404e248f5b9fee9fe5f771f4cb829f5f1c39

Frozen

16 Oct, 13:51

Nothing in the definition can change after this.

Confounders

• Field size: marathon handicaps often have big fields, which raises the win odds of every runner and can push A/E up at long prices for reasons unrelated to the horse
• Festival handicaps (Cheltenham, Aintree, Punchestown, the Irish and Welsh Nationals): a few big races can supply most of the winners, so the selection may be measuring a race type and not a step-up effect. The same-race control and per-race concentration need checking
• Weight carried: young, lightly raced handicappers may be low in the weights, so a low-weight effect could pass for a stamina effect
• Trainer concentration: a few yards that place young stayers well (Mullins, Elliott, Nicholls and similar) could carry the lift
• Period decay: H175 fell to 1.05 in its latest period, and other threads show lifts tied to one spring. Results must be read per season
• Price-band concentration: a lift from a handful of 16/1+ winners is the failure pattern seen elsewhere in the lab
• Last run in a different code (a hurdle or point-to-point) also passes last_distance_yards < 6160, so the step-up group mixes code-switchers with true chase trip step-ups

Discovery result

pass broad rule (niche) · 16 Oct, 13:46

Bets

97

13 winners

A/E

1.11

95%: 0.59 to 1.91

SP return

-0.5%

level stakes

Betfair SP return

+23.9%

97 bets with a BSP

Strike rate 13.4%. p = 0.39. Same-race control: the other runners in these races had A/E 0.97, so the selection beat its own races. Zone: discovery. Evaluator eval-1.0, data 6a4e98be18e83933

Falsification

Each attack is a deliberate attempt to kill the idea. 3 of 5 survived.

• control: Control: young marathon handicap chasers already run at 3m4f+ last timeinfo

  24 bets · A/E 1.18 (0.24 to 3.43) · control 0.99 · 16 Oct, 13:51

  Breakdown

  betsA/E0.71.01.3

  2025-10-01 to 2026-04-2721–

  after 2026-04-273–

• partition: Partition: true chase trip step-ups only (last run was a chase)pass

  93 bets · A/E 1.06 (0.55 to 1.85) · control 0.99 · 16 Oct, 13:51

  Breakdown

Sealed holdout (vault)

Bets

384

16 Oct, 13:51

A/E

1.22

p = 0.095

BH threshold then

0.0025

over every vault test so far

Outcome

Failed

Forward record

• forward vs bar {'min_bets': 100, 'min_ae': 1.0, 'max_p': 0.2}info

  0 bets · · 16 Oct, 13:51

  Breakdown

  betsA/E0.71.01.3

  forward0–

Other experiments

• neighbour: <= 7 -> 6 (-20%)pass

  23 bets · A/E 1.59 (0.52 to 3.72) · control 0.84 · 16 Oct, 13:51

  Breakdown

  betsA/E0.71.01.3

  2025-10-01 to 2026-04-2723–

  after 2026-04-270–

• neighbour: <= 7 -> 8 (+20%)fail

  186 bets · A/E 0.88 (0.51 to 1.40) · control 1.15 · 16 Oct, 13:51

  Breakdown

  bets

Lineage

Agent runs

• designer v1ok · 53s · 16 Oct, 13:44

  Output (schema-checked)

  {
    "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND distance_yards >= 6160 AND last_distance_yards < 6160",
    "refinements": [
      {
        "label": "no previous runs at the trip (closest to a true first try at 3m4f+)",
        "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND distance_yards >= 6160 AND last_distance_yards < 6160 AND runs_at_trip = 0"
      },
      {
        "label": "14/1 or shorter (edges in this lab tend to die or turn to noise at big prices)",
        "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND distance_yards >= 6160 AND last_distance_yards < 6160 AND sp_decimal <= 15"
      }
    ],
    "control": {
      "description": "The main control asks whether the step-up is what matters, so it uses young (age <= 7) handicap chasers in 3m4f+ chases whose last run was already at 3m4f+. If the mechanism holds, the step-up rule should beat this group clearly. If both show a similar A/E (around 1.15, like H175), the lift belongs to young horses in marathon chases in general and not to unproven stamina, and the hypothesis is falsified. The lab's standard same-race comparison (the other runners in these races) should show A/E near 1.0 or a little below. If those other runners also score well above 1.0, the lift is a property of the races (big-field festival marathon handicaps, the rival H-8b0e3766) and not of the selected horses.",
      "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND distance_yards >= 6160 AND last_distance_yards >= 6160"
    },
    "pass_criteria": {
      "min_bets": 200,
      "min_ae": 1.05,
      "max_p": 0.05
    },
    "forward_bar": {
      "min_bets": 100,
      "min_ae": 1,
      "max_p": 0.2
    },
    "confounders": [
      "Field size: marathon handicaps often have big fields, which raises the win odds of every runner and can push A/E up at long prices for reasons unrelated to the horse",
      "Festival handicaps (Cheltenham, Aintree, Punchestown, the Irish and Welsh Nationals): a few big races can supply most of the winners, so the selection may be measuring a race type and not a step-up effect. The same-race control and per-race concentration need checking",
      "Weight carried: young, lightly raced handicappers may be low in the weights, so a low-weight effect could pass for a stamina effect",
      "Trainer concentration: a few yards that place young stayers well (Mullins, Elliott, Nicholls and similar) could carry the lift",
      "Period decay: H175 fell to 1.05 in its latest period, and other threads show lifts tied to one spring. Results must be read per season",
      "Price-band concentration: a lift from a handful of 16/1+ winners is the failure pattern seen elsewhere in the lab",
      "Last run in a different code (a hurdle or point-to-point) also passes last_distance_yards < 6160, so the step-up group mixes code-switchers with true chase trip step-ups"
    ],
    "mechanism": "Young chasers (7 or under) are often still improving physically and have more stamina than their runs at shorter trips have yet shown. When such a horse steps up to 3m4f or more in a handicap chase for the first time (its last run was shorter), the extra trip unlocks ability its form does not yet show. This lift should be larger than for young horses whose stamina for the trip has already been tested in public.",
    "market_miss": "Prices are set from a form book that shows only shorter-trip runs, often one-paced or beaten late. Those runs read as a lack of stamina at exactly the moment the longer trip suits the horse. Layers and punters also follow the belief that marathons need seasoned, proven stayers. So the young horse that is unproven at the trip is the runner they doubt most, and its price drifts beyond its true chance. Once the horse has run at 3m4f+, that proof is in the form and the mispricing should shrink.",
    "prediction": {
      "direction": "positive",
      "size": "A/E 1.15 to 1.30 on 250+ bets, clearly above the young runners whose last run was already at 3m4f+",
      "falsified_if": "A/E at or below 1.05 for the broad rule, or no higher than the control group of young runners whose last run was already at 3m4f+, or a lift that comes almost entirely from 16/1+ winners or from a single season"
    },
    "notes": "I kept the rule sketch as written. It uses only pre-off columns (distance_yards and last_distance_yards are both available from 2020-07). last_distance_yards < 6160 means the last run was shorter, which is not the same as a first ever run at 3m4f+. The catalogue has no career-longest-trip column, so the runs_at_trip = 0 refinement is the nearest available version of 'first time at the trip'. Its exact definition (which trip band it counts) is not documented, so read it with care. Horses with no previous run have a NULL last_distance_yards and drop out of the rule. I raised min_bets to 200 because the prediction calls for 250+ bets. This hypothesis puts H175's reversed (positive) finding to a direct mechanism test, as the findings asked."
  }

Timeline

1. Job 1713 finished

   16 Oct, 13:51 · engine:compute-1

2. forward result for H-98848406 (forward vs bar {'min_bets': 100, 'min_ae': 1.0, 'max_p': 0.2}): info

   16 Oct, 13:51 · engine:evaluator

3. compute-1 took job 1713 (forward_check, attempt 1)

   16 Oct, 13:51 · compute-1

4. Queued forward_check on the compute lane: daily forward check of a shadow system

   16 Oct, 13:51 · engine:scheduler

5. Job 1684 finished

   16 Oct, 13:51 · engine:compute-1

6. hypothesis note H-98848406

   16 Oct, 13:51 · engine:perturb

7. perturbation result for H-98848406 (neighbour: < 6160 -> 7392 (+20%)): pass

   16 Oct, 13:51 · engine:perturb

8. perturbation result for H-98848406 (neighbour: < 6160 -> 4928 (-20%)): pass

   16 Oct, 13:51 · engine:perturb

9. perturbation result for H-98848406 (neighbour: >= 6160 -> 7392 (+20%)): fail

   16 Oct, 13:51 · engine:perturb

10. perturbation result for H-98848406 (neighbour: >= 6160 -> 4928 (-20%)): pass

    16 Oct, 13:51 · engine:perturb

11. perturbation result for H-98848406 (neighbour: <= 7 -> 8 (+20%)): fail

    16 Oct, 13:51 · engine:perturb

12. perturbation result for H-98848406 (neighbour: <= 7 -> 6 (-20%)): pass

    16 Oct, 13:51 · engine:perturb

13. compute-1 took job 1684 (mutate, attempt 1)

    16 Oct, 13:51 · compute-1

14. Job 1711 finished

    16 Oct, 13:51 · engine:compute-1

15. H-98848406 Vault → SHADOW vault SUPPORTIVE: A/E 1.215 on 384 bets, p 0.09455 against BH threshold 0.0025 over 40 vault tests

    16 Oct, 13:51 · engine:orchestrator

16. vault result for H-98848406 (vault query (supportive)): pass

    16 Oct, 13:51 · engine:orchestrator