Lightly raced young chasers at 3m to 3m3f in handicaps are over-bet as progressive improvers

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
   • H-910e15e3 (Dose-response: young handicap chasers at 3m to 3m3f show a smaller lif) was predicted positive but came out the other way: A/E 0.92 on 971 bets (p 0.187 for the opposite direction). O-1a183ac0
2. AskedIs the young-horse shortfall at 3m to 3m3f (A/E 0.92) concentrated in lightly raced chasers bought as progressive handicappers? answered
3. MechanismYoung chasers early in their handicap careers are backed for expected improvement. At standard staying trips the handicapper has often caught them already, and lack of jumping experience costs them in competitive fields.
4. Why the market misses itA novice-season win or a good debut chase makes the horse look unexposed and well treated. The market prices in improvement that has already been used up by the mark.
5. Predictednegative, A/E 0.82 to 0.92 on 400+ bets
6. Falsified ifA/E at or above 0.97, or no lower than young runners at the same trips with 4 or more chase runs
7. Rule sketchrace_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs <= 3 AND distance_yards >= 5280 AND distance_yards < 6160
8. question idQ-45d590ce
9. operator

The question's answer so far: No. Young handicap chasers at 3m to 3m3f with three or fewer chase runs score 0.95 on 472, no lower than the 0.92 for all young runners there. The shortfall is not carried by the lightly raced 'progressive improver' group, and if anything sits slightly more in the experienced young chasers.

Mechanism and rationale

Young chasers early in their handicap careers are backed for expected improvement. At standard staying trips the handicapper has often caught them already, and lack of jumping experience costs them in competitive fields.

The rule

race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs <= 3 AND distance_yards >= 5280 AND distance_yards < 6160

Reads: race_type, is_handicap, age, chase_runs, distance_yards

Pre-registration

Spec hash (sha256 of the canonical pre-spec)

3abacecae374fc1839657bb8d7040d46fc524aec3e15782934860564668b325b

Frozen

not frozen

The definition can still change.

Confounders

• Field size: big competitive handicaps may punish inexperienced jumpers whatever the price, so check whether the effect sits only in 10+ runner fields
• Race class: lightly raced young chasers may be concentrated in better-class novice handicaps, where pricing behaves differently
• Trainer concentration: a few big yards place many young chasers in handicaps early, and their runners are often over-bet
• Irish pricing: the parent rule scored 0.83 in IRE, so a country split must not be the whole effect
• chase_runs counts only from July 2020, so in early seasons some horses with more chase runs are counted as lightly raced. age <= 7 limits this, but check the effect by period
• Seasonal timing: novice-handicap targets cluster in the spring festival period, so check that the effect is not one spring window
• Overlap with the parent rule (0.92 on 971): if the young horses with 4+ chase runs also score about 0.92, the low score is about age at the trip, not inexperience

Control

{
  "description": "Primary control: young (age <= 7) handicap chasers at the same 3m to 3m3f trips with 4 or more chase runs. The mechanism says inexperience is what the market overprices, so the lightly raced group must score clearly below this group. The parent rule's same-race control was 1.10, so other runners in the same races should be about 1.0 to 1.10. If the lightly raced group's A/E is not below both, the effect is a property of these races or of young horses at the trip, not of chase inexperience.",
  "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs >= 4 AND distance_yards >= 5280 AND distance_yards < 6160"
}

Discovery result

fail broad rule · 16 Oct, 13:51

Bets

472

72 winners

A/E

0.95

95%: 0.74 to 1.20

SP return

-29.1%

level stakes

Betfair SP return

-15.1%

456 bets with a BSP

Strike rate 15.3%. p = 0.68. Same-race control: the other runners in these races had A/E 1.04, so the selection did not beat its own races. Zone: discovery. Evaluator eval-1.0, data 6a4e98be18e83933

Falsification

No attacks yet. Only promising ideas are attacked.

Sealed holdout (vault)

Not queried. Only a frozen idea can spend its one query against the 2020-25 holdout.

Forward record

No forward record. Shadow tracking starts after the vault and counts only races run after the freeze.

Lineage

Agent runs

• designer v1ok · 30s · 16 Oct, 13:48

  Output (schema-checked)

  {
    "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs <= 3 AND distance_yards >= 5280 AND distance_yards < 6160",
    "refinements": [
      {
        "label": "backed improvers: 14/1 or shorter",
        "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs <= 3 AND distance_yards >= 5280 AND distance_yards < 6160 AND sp_decimal <= 15"
      },
      {
        "label": "competitive fields: 10+ runners",
        "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs <= 3 AND distance_yards >= 5280 AND distance_yards < 6160 AND field_size >= 10"
      }
    ],
    "control": {
      "description": "Primary control: young (age <= 7) handicap chasers at the same 3m to 3m3f trips with 4 or more chase runs. The mechanism says inexperience is what the market overprices, so the lightly raced group must score clearly below this group. The parent rule's same-race control was 1.10, so other runners in the same races should be about 1.0 to 1.10. If the lightly raced group's A/E is not below both, the effect is a property of these races or of young horses at the trip, not of chase inexperience.",
      "rule": "race_type = 'Chase' AND is_handicap = 1 AND age <= 7 AND chase_runs >= 4 AND distance_yards >= 5280 AND distance_yards < 6160"
    },
    "pass_criteria": {
      "min_bets": 300,
      "min_ae": 1.05,
      "max_p": 0.05
    },
    "forward_bar": {
      "min_bets": 100,
      "min_ae": 1,
      "max_p": 0.2
    },
    "confounders": [
      "Field size: big competitive handicaps may punish inexperienced jumpers whatever the price, so check whether the effect sits only in 10+ runner fields",
      "Race class: lightly raced young chasers may be concentrated in better-class novice handicaps, where pricing behaves differently",
      "Trainer concentration: a few big yards place many young chasers in handicaps early, and their runners are often over-bet",
      "Irish pricing: the parent rule scored 0.83 in IRE, so a country split must not be the whole effect",
      "chase_runs counts only from July 2020, so in early seasons some horses with more chase runs are counted as lightly raced. age <= 7 limits this, but check the effect by period",
      "Seasonal timing: novice-handicap targets cluster in the spring festival period, so check that the effect is not one spring window",
      "Overlap with the parent rule (0.92 on 971): if the young horses with 4+ chase runs also score about 0.92, the low score is about age at the trip, not inexperience"
    ],
    "mechanism": "Young chasers with three or fewer chase runs, running in handicaps at 3m to 3m3f, are backed for improvement still to come. At these standard staying trips the handicapper has usually already rated their novice form. Their lack of jumping experience also costs them in competitive handicap fields, so they win less often than their prices imply.",
    "market_miss": "A novice-season win or a promising chase debut makes the horse look unexposed and well treated. Punters and the market price in improvement that the official mark has already absorbed, and they underweight the jumping-experience cost in a big handicap field.",
    "prediction": {
      "direction": "negative",
      "size": "A/E 0.82 to 0.92 on 400+ bets, below young runners with 4+ chase runs at the same trips",
      "falsified_if": "A/E at or above 0.97, or A/E no lower than the control (age <= 7, chase_runs >= 4, same trips and handicap condition)"
    },
    "notes": "This tests whether the parent rule's 0.92 at 3m to 3m3f (H-910e15e3, 971 bets) is carried by horses with little chase experience. It is pre-registered as negative (over-bet), so the pass thresholds apply in the over-bet direction. min_bets was raised to 300 because the prediction expects 400+ bets. Refinements are read only if the broad rule shows evidence, and the price-band caution from the step-up findings applies. The rule uses only pre-off columns, and chase_runs is available from GB/IRE 2020-08."
  }

Timeline

1. Job 1691 finished

   16 Oct, 13:51 · engine:compute-1

2. H-717bd1f9 Discovery → KILLED fails: A/E 0.952, needs 0.95 or lower; p 0.3652 (lower tail), needs 0.05

   16 Oct, 13:51 · engine:evaluator

3. discovery result for H-717bd1f9 (broad rule): fail

   16 Oct, 13:51 · engine:evaluator

4. H-717bd1f9 Designed → RESEARCHdiscovery measuring on the discovery zone

   16 Oct, 13:51 · engine:orchestrator

5. compute-1 took job 1691 (evaluate, attempt 1)

   16 Oct, 13:51 · compute-1

6. Job 1689 finished

   16 Oct, 13:48 · engine:ai-1

7. Queued evaluate on the compute lane: discovery run of the broad rule

   16 Oct, 13:48 · engine:scheduler

8. H-717bd1f9 Proposed → RESEARCHdesigned pre-spec written and hashed

   16 Oct, 13:48 · agent:designer@v1

9. ai-1 took job 1689 (design, attempt 1)

   16 Oct, 13:48 · ai-1

10. Queued design on the ai lane: write the pre-spec

    16 Oct, 13:47 · engine:scheduler

11. New idea H-717bd1f9: Lightly raced young chasers at 3m to 3m3f in handicaps are over-bet as progressive improvers (test-mechanism)

    16 Oct, 13:47 · agent:investigator@v1

Every change is an event with an actor: an agent and its version, an engine, a human, or the importer. Current stage: Killed.