Predicted maturity offset and age at peak height velocity (PHV) were dependent upon chronological age and probably size at prediction; predicted offset systematically decreased and age at PHV systematically increased with chronological age at prediction.

Variation in predicted ages at PHV with the new equations was systematically reduced compared with predictions with the original equations and observed ages at PHV.

Predicted age at PHV with the new equations was quite accurate for average maturing boys within ±1 year of observed PHV; a corresponding window for average maturing girls was not apparent.

Predicted ages at PHV were systematically later than observed ages at PHV in early maturing boys and girls, and systematically earlier than observed ages at PHV in late maturing boys and girls.

The Bland–Altman regressions indicated a lack of fit between predicted and observed ages at PHV within each chronological age group and within each year before and after PHV; slopes for the new equations were greater than those for the original equations.

Intra-individual variation in predicted ages at PHV with the new and original equations was considerable.