Table 3.

Mean error and absolute mean error and root mean squared error and 95 % confidence intervals validating the Willems et al. (BC) method, overall and sex specific

Sex	N		Mean	SD	P
M + F	1146	Chronological Age	10.31	4.00	0.6653
		Estimated age	10.28	3.51
		Error	0.02	1.78
		RMSE (95 %Cl)	1.7780 (1.711;1.845)	–
M	605	Chronological Age	10.50	4.04	0.5055
		Estimated age	10.50	3.50
		Error	− 0.01	1.76
		Absolute Error	1.34	1.13
		RMSE (95 %Cl)	1.7582 (1.667;1.849)	–
F	541	Chronological Age	10.09	3.96	0.1560
		Estimated age	10.03	3.51
		Error	0.06	1.80
		Absolute Error	1.33	1.22
		RMSE (95 %Cl)	1.8003 (1.700;1.900)	–

N: Number; M: total number of male subjects; F: total number of female subjects; Descriptive statistics for chronological age based on the method by Willems et al. [11] and for the (absolute) error between chronological age and estimated age: mean age and standard deviation (SD); RMSE: root mean squared error; 95 %CI: 95 % confidence intervals for RMSE; P: p-value from Wilcoxon signed rank test comparing age and age estimation based on Willems et al. (2001) [3]