Table. 4: Prediction errors related to the proposed empirical model.

#	Observed FM			Pred FM	Pred/ test
		(MPa)0.5	(MPa)0.5
1	J	0.49	0.51	J	1.00
2	J	0.44	0.55	J	1.17
3	J	0.39	0.54	J	1.53
4	J	0.38	0.52	J	1.14
5	BJ	0.39	0.44	BJ	1.03
6	BJ	0.44	0.46	BJ	0.99
7	BJ	0.44	0.46	BJ	0.95
8	BJ	0.53	0.47	J	0.85
9	BJ	0.43	0.46	BJ	0.95
10	BJ	0.42	0.46	BJ	1.01
11	J	0.57	0.69	J	0.77
12	BJ	0.38	0.51	BJ	1.05
13	J	0.62	0.77	J	0.82
14	J	0.60	0.60	J	0.85
15	J	0.50	0.68	J	0.77
16	J	0.34	0.53	J	1.12
ALL				mean	1.00
				CoV	0.19
J				mean	1.02
				CoV	0.25
BJ				mean	0.97
				CoV	0.07