Table 3. Correlation (Pearson) analysis of 6 main head traits in DH population.

Traits	Hm	Hvd	Htd	Hsi	Hw	Hsr
Hm (day)	1	0.126	0.036	-0.282**	-0.379**	0.148
Hvd (cm)		1	0.790**	0.383**	0.852**	-0.308**
Htd (cm)			1	-0.258**	0.909**	-0.250**
Hsi				1	-.025	-0.104
Hw (kg)					1	-0.388**
Hsr						1

Hm head mature period, Hw head weight, Hvd head vertical diameter, Htd head transverse diameter, Hsi head shape index.

*Correlation is significant at the 0.05 level (2-tailed).

**Correlation is significant at the 0.01 level (2-tailed).