The risk of injury associated with body checking among Pee Wee ice hockey players: an evaluation of Hockey Canada’s national body checking policy change
Bibliographic record
Abstract
BACKGROUND: In 2013, Hockey Canada introduced an evidence-informed policy change delaying the earliest age of introduction to body checking in ice hockey until Bantam (ages 13-14) nationwide. OBJECTIVE: To determine if the risk of injury, including concussions, changes for Pee Wee (11-12 years) ice hockey players in the season following a national policy change disallowing body checking. METHODS: In a historical cohort study, Pee Wee players were recruited from teams in all divisions of play in 2011-2012 prior to the rule change and in 2013-2014 following the change. Baseline information, injury and exposure data for both cohorts were collected using validated injury surveillance. RESULTS: Pee Wee players were recruited from 59 teams in Calgary, Alberta (n=883) in 2011-2012 and from 73 teams in 2013-2014 (n=618). There were 163 game-related injuries (incidence rate (IR)=4.37/1000 game-hours) and 104 concussions (IR=2.79/1000 game-hours) in Alberta prior to the rule change, and 48 injuries (IR=2.16/1000 game-hours) and 25 concussions (IR=1.12/1000 game-hours) after the rule change. Based on multivariable Poisson regression with exposure hours as an offset, the adjusted incidence rate ratio associated with the national policy change disallowing body checking was 0.50 for all game-related injuries (95% CI 0.33 to 0.75) and 0.36 for concussion specifically (95% CI 0.22 to 0.58). CONCLUSIONS: Introduction of the 2013 national body checking policy change disallowing body checking in Pee Wee resulted in a 50% relative reduction in injury rate and a 64% reduction in concussion rate in 11-year-old and 12-year-old hockey players in Alberta.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.013 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".