Table 2.

Descriptive statistics.

Variables	N	Mean	SD	Min	Median	Max
$\theta$	486	0.040	0.032	0.001	0.027	0.136
$x_1$	486	7.860	1.019	3.481	7.866	10.077
$x_2$	486	12.550	0.430	11.515	12.537	14.097
$z_1$	486	1.850	1.261	0.240	1.601	11.714
$z_2$	486	7.190	0.600	5.257	7.230	8.661
$z_3$	486	2.780	0.581	0.000	2.890	4.043
$m_1$	486	11.870	1.179	2.691	11.994	13.399
$m_2$	486	13.050	1.188	4.711	13.198	16.165