Juvenile stature estimation is a different science.

What you see in the calculator

If you select the Subadult Beta module the calculator displays a notice and refuses to compute an adult-style result. This is intentional. Antrometric V3.1 will not apply adult linear regression coefficients to juvenile remains because the underlying biological assumption no longer holds. The button is present so the boundary is visible to every user, not hidden behind a disclaimer.

Why adult formulas fail on juvenile remains

Adult stature regressions assume that the measured long bone has reached mature length, that growth plates have fused, and that the relationship between bone length and adult stature can be treated as linear within adult variation. Those assumptions do not hold during growth. Diaphyseal growth is not constant across childhood, epiphyses fuse at different times, and body proportions change with maturity. Applying adult coefficients to juveniles can therefore create biased estimates with misleadingly narrow intervals.

What a modern subadult model requires

A defensible subadult stature estimator needs model architecture that the current V3.1 adult engine does not contain.

1. Growth-aware regression. Chu and Stull (2025) show that subadult stature estimation benefits from linear and nonlinear models that account for the shape of growth rather than simply reusing adult slopes.
2. Appropriate subadult measurements. Their work evaluates long bone lengths and breadths from a contemporary CT sample and provides equations specifically built for subadult stature.
3. Usable prediction intervals. A juvenile result must include intervals that reflect growth variability. A narrow adult-style interval would be misleading.

The literature Antrometric is reading for future subadult research

• Smith and Buschang (1994). Documents variation in longitudinal diaphyseal long bone growth in children three to ten years of age. This supports the boundary between adult and growing-skeleton logic.
• Chu and Stull (2025). Provides contemporary subadult stature equations using a large CT sample, linear and nonlinear modeling, and usable prediction intervals. This is the most directly relevant current reference for a future Antrometric subadult engine.
• Panel regression approaches. Age-structured statistical work on immature skeletons shows that subadult estimation can be modeled without simply copying adult formulas, but those methods must be implemented and documented explicitly before use.

Why a placeholder is more honest than a guess

It would be technically simple to wire the Subadult button to a juvenile equation set and print a number. That would not be enough. A juvenile stature estimate must know which model it is using, which measurements it accepts, what age or growth structure it requires, and how the interval was validated. Until that exists inside Antrometric, refusing to calculate is the scientifically correct behavior.

Future research roadmap

• Implement a subadult model only from citable equations with documented prediction intervals.
• Separate subadult input fields from adult input fields so the two workflows cannot be confused.
• Document measurement definitions, age or growth assumptions, sample coverage, and interval behavior.
• Add a juvenile-specific consistency diagnostic only after the model supports multi-measurement comparison.
• Keep adult results and subadult results visually and mathematically separated.

References

1. Chu, E. Y., & Stull, K. E. (2025). An investigation of the relationship between long bone measurements and stature: Implications for estimating skeletal stature in subadults. International Journal of Legal Medicine, 139, 441-453. https://doi.org/10.1007/s00414-024-03336-7
2. Smith, S. L., & Buschang, P. H. (1994). Variation in longitudinal diaphyseal long bone growth in children three to ten years of age. American Journal of Human Biology, 6, 651-668.