Cross-National Trends in Early Sexual Initiation Among 15-Year-Old Adolescents, 2002–2022
Bibliographic record
Abstract
Objectives: We examined how the proportion of adolescents who engaged in early sexual intercourse (before the age of 14) changed between 2002 and 2022 across 37 countries. Methods: = 312,702). We used uni- and multivariate multilevel binary logistic regression models to test whether rates of early sexual initiation changed over time. Country, gender, family affluence, parental support and the clustering effect of school were incorporated in the statistical models; linearity was tested by cubic and quadratic terms in the multivariate models. Results: A significant but very small decline over time was found in early sexual initiation across survey years. Girls and less affluent adolescents had lower odds of early initiation. Parental support (and its interaction with time) also had a significant but small protective role. Conclusion: Despite a small decrease over time, still 4% of participants reported early sexual initiation in 2022. Concerted and sustained efforts are needed to support adolescent sexual health.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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".