Secular trends in the body mass index of Canadian children.
Bibliographic record
Abstract
BACKGROUND: Various changes in society have created the opportunity for more sedentary behaviour and the consumption of food that is high in kilojoules, which may lead to a progressive increase in body mass over time. The purpose of this study was to examine secular changes in the body mass index (BMI) of Canadian children between 1981 and 1996. METHODS: Nationally representative data from the 1981 Canada Fitness Survey, the 1988 Campbell's Survey on the Well-being of Canadians and the 1996 National Longitudinal Survey of Children and Youth were used in the analysis. Regression analyses were used to assess population changes in BMI from 1981 to 1996 for children aged 7-13 years. Changes in the distribution of BMI results were evaluated by plotting the residuals from regression analyses of BMI on age, assessed separately by sex, using the 1981 data as baseline. The proportions of children exceeding the 85th and 95th age- and sex-specific percentiles from the 1981 (baseline) data were also calculated. RESULTS: Since 1981, BMI has increased at the rate of nearly 0.1 kg/m2 per year for both sexes at most ages, indicating a clear secular trend toward an increase in BMI of Canadian children. The prevalence of overweight among boys increased from 15% in 1981 to 28.8% in 1996 and among girls from 15% to 23.6%. The prevalence of obesity in children more than doubled over that period, from 5% to 13.5% for boys and 11.8% for girls. INTERPRETATION: Secular trends indicate that Canadian children aged 7-13 years are becoming progressively overweight and obese.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.006 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".